Eastern U.S. Continental Shelf Carbon Budget: Integrating Models,Data Assimilation, and Analysis

NASA Technical Reports Server (NTRS)

Hofmann, Eileen; Mannino, Antonio; McClain, Charles R.

2007-01-01

The U.S. East Coast Continental Shelf (USECoS) project was initiated in 2004 with the overall goal of developing carbon budgets for Mid-Atlantic and South Atlantic regions of the eastern U.S. coast. We addressed this goal through a series of specific research questions that were designed to understand carbon inputs and fates in the two regions, dominant food web pathways for carbon cycling, and similarities/differences in carbon cycling in the two continental shelf systems. The USECoS project represents a major effort to simultaneously synthesize and integrate diverse data sets, field measurements, models, and modeling approaches. We expect that the type of approach taken here will result in more insight than would be possible if each component of the program moved forward independently. The primary significance of this project is in providing a strong quantitative basis for the development of future observational and modeling studies of carbon budgets of continental shelf systems. A strong aspect of the USECoS project is the integration of modeling and extensive physical, chemical, and biological data sets, which provides an opportunity for modeling and data analyses to inform one another from the outset. This research is particularly germane to NASA's carbon cycle research focus and coastal research initiative and the U.S. Climate Change Research Program, all of which support the goals of the North American Carbon Program. We highlight primary approaches that have been used, and some of the challenges and results that have come from interactions among our team of investigators. The global scale and interdisciplinary nature of the science questions that we now face in Earth Science are such that integrated teams of investigators are needed to address them.

Estimation of forest canopy nitrogen concentration. Chapter 15

Treesearch

Marie-Louise Smith; David Y. Hollinger; Scott Ollinger

2008-01-01

The ability to detect patterns of carbon assimilation by vegetation is a key component of the North American Carbon Program. Because photosynthetic potential is strongly related to biochemical constituents such as nitrogen and chlorophyll concentrations in foliage, the ability to incorporate canopy chemistry into landscape- to regional-scale carbon cycling research...

Permeability testing of composite material and adhesive bonds for the DC-XA composite feedline program

NASA Technical Reports Server (NTRS)

Nettles, A. T.

1995-01-01

Hercules IM7/8552 carbon/epoxy and Hysol EA 9394 epoxy adhesive bonded between composite/titanium were tested for permeability after various numbers of thermal cycles between 100 C and liquid nitrogen (-196 C). The specimens were quenched from the 100 C temperature into liquid nitrogen to induce thermal shock into the material. Results showed that the carbon/epoxy system was practically impermeable even after 12 thermal cycles. The EA 9394 adhesive bondline was more permeable than the carbon/epoxy, but vacuum mixing minimized the permeability and kept it within allowable limits. Thermal cycling had little effect on the permeability values of the bondline specimens.

The U.S. Climate Change Science Program. Vision for the Program and Highlights of the Scientific Strategic Plan

DTIC Science & Technology

2003-07-01

CH4, N2O, O3, etc. Aerosols Clouds ATMOSPHERIC COMPOSITION WATER CYCLE LAND-USE/ LAND-COVER CHANGE HUMAN CONTRIBUTIONS AND RESPONSES CARBON...Oceanographic Institution. Climate Variability and Change ATMOSPHERIC COMPOSITION CLIMATE VARIABILITY AND CHANGE GLOBAL WATER CYCLE LAND-USE/LAND-COVER CHANGE...their access to and use of water. CCSP-supported research on the global water cycle focuses on how natural processes and human activities influence the

From the field to classrooms: Scientists and educators collaborating to develop K-12 lessons on arctic carbon cycling and climate change that align with Next Generation Science Standards, and informal outreach programs that bring authentic data to informal audiences.

NASA Astrophysics Data System (ADS)

Brinker, R.; Cory, R. M.

2014-12-01

Next Generation Science Standards (NGSS) calls for students across grade levels to understand climate change and its impacts. To achieve this goal, the NSF-sponsored PolarTREC program paired an educator with scientists studying carbon cycling in the Arctic. The data collection and fieldwork performed by the team will form the basis of hands-on science learning in the classroom and will be incorporated into informal outreach sessions in the community. Over a 16-day period, the educator was stationed at Toolik Field Station in the High Arctic. (Toolik is run by the University of Alaska, Fairbanks, Institute of Arctic Biology.) She participated in a project that analyzed the effects of sunlight and microbial content on carbon production in Artic watersheds. Data collected will be used to introduce the following NGSS standards into the middle-school science curriculum: 1) Construct a scientific explanation based on evidence. 2) Develop a model to explain cycling of water. 3) Develop and use a model to describe phenomena. 4) Analyze and interpret data. 5) A change in one system causes and effect in other systems. Lessons can be telescoped to meet the needs of classrooms in higher or lower grades. Through these activities, students will learn strategies to model an aspect of carbon cycling, interpret authentic scientific data collected in the field, and conduct geoscience research on carbon cycling. Community outreach sessions are also an effective method to introduce and discuss the importance of geoscience education. Informal discussions of firsthand experience gained during fieldwork can help communicate to a lay audience the biological, physical, and chemical aspects of the arctic carbon cycle and the impacts of climate change on these features. Outreach methods will also include novel use of online tools to directly connect audiences with scientists in an effective and time-efficient manner.

A life cycle carbon dioxide inventory of the Million Trees Los Angeles Program

Treesearch

E. Gregory McPherson; Alissa Kendall

2014-01-01

PurposeThis study seeks to answer the question, “Will the Million Trees LA (Million Trees Los Angeles, MTLA) program be a carbon dioxide (CO2) sink or source?” Because there has never been a full accounting of CO2 emissions, it is unclear if urban tree planting initiatives (TPIs) are likely to be...

Process modeling for carbon-phenolic nozzle materials

NASA Technical Reports Server (NTRS)

Letson, Mischell A.; Bunker, Robert C.; Remus, Walter M., III; Clinton, R. G.

1989-01-01

A thermochemical model based on the SINDA heat transfer program is developed for carbon-phenolic nozzle material processes. The model can be used to optimize cure cycles and to predict material properties based on the types of materials and the process by which these materials are used to make nozzle components. Chemical kinetic constants for Fiberite MX4926 were determined so that optimization of cure cycles for the current Space Shuttle Solid Rocket Motor nozzle rings can be determined.

Assessing seven decades of carbon accumulation in two U.S. northern hardwood forests

Treesearch

Coeli Hoover

2011-01-01

Forests play a key role in the global carbon cycle, and programs aimed at mitigating greenhouse gas emissions through the protection and enhancement of forest carbon stocks are growing in number. Adding greenhouse gas mitigation as a management objective presents managers with a considerable challenge, because data and guidelines are scarce. Long-term inventory...

Providing policy-relevant information for greenhouse gas management: Perspectives from science and technology policy research

NASA Astrophysics Data System (ADS)

Dilling, L.

2009-12-01

In the 12 years since the Kyoto Protocol was signed setting forth targets for greenhouse gas emissions from several nations, the number of policies, voluntary programs and commercial enterprises that have developed to manage carbon has grown exponentially. Many of these programs have occurred in a voluntary context, such as carbon trading, carbon offset programs, and climate registries . To date, no single, common system for accrediting, verifying and recording carbon credits has developed. Moreover, as the international community continues to negotiate the dimensions of an international agreement for the post-Kyoto time period, discussions still center on targets for fossil fuel emissions, biospheric carbon protection, and appropriate distribution of the burden of compliance globally. If carbon still remains the currency for discussion in a climate agreement, some type of effective measurement and verification system will be needed to ensure that commitments are being met. While entire volumes over the past decade have been written on what it is possible to observe about the carbon cycle and how to do so-- these tend to describe observations from the perspective of studying the carbon cycle to discover fundamental new knowledge. I will argue, however, that for the application under consideration in this session, i.e. a global greenhouse gas information system, it is essential to bring in the perspective of the policy and regulatory community. The needs of the scientific community for measuring the uncertainties in the global carbon cycle are not necessarily the same as those for the policy community. To ensure that such a system can serve a policy-relevant function, the scientific community must engage with policy makers, entrepreneurs, those who must comply, and others involved in constructing the policy framework. This paper will examine some of the key fundamentals that the policy community may be considering in designing a greenhouse gas monitoring system. I will discuss some of the key elements of successful interactions between science and policy, as well as some specifics for the carbon management context. I will draw on case studies of previous monitoring efforts developed for policy and illustrate some of the key elements to be considered as well as lessons learned. The paper will also examine how the carbon context may be different from other contexts we have encountered in the past. Finally, I will conclude with some implications for structuring decision support science policies within the U.S. Global Change Research Program and other related programs.

40 CFR 86.1524 - Carbon dioxide analyzer calibration.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 20 2013-07-01 2013-07-01 false Carbon dioxide analyzer calibration. 86.1524 Section 86.1524 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) CONTROL OF EMISSIONS FROM NEW AND IN-USE HIGHWAY VEHICLES AND ENGINES (CONTINUED) Emission Regulations for Otto-Cycle Heavy-Duty...

40 CFR 86.1522 - Carbon monoxide analyzer calibration.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 20 2013-07-01 2013-07-01 false Carbon monoxide analyzer calibration. 86.1522 Section 86.1522 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) CONTROL OF EMISSIONS FROM NEW AND IN-USE HIGHWAY VEHICLES AND ENGINES (CONTINUED) Emission Regulations for Otto-Cycle Heavy-Duty...

40 CFR 86.1522 - Carbon monoxide analyzer calibration.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 19 2011-07-01 2011-07-01 false Carbon monoxide analyzer calibration. 86.1522 Section 86.1522 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) CONTROL OF EMISSIONS FROM NEW AND IN-USE HIGHWAY VEHICLES AND ENGINES (CONTINUED) Emission Regulations for Otto-Cycle Heavy-Duty...

40 CFR 86.1524 - Carbon dioxide analyzer calibration.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 19 2011-07-01 2011-07-01 false Carbon dioxide analyzer calibration. 86.1524 Section 86.1524 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) CONTROL OF EMISSIONS FROM NEW AND IN-USE HIGHWAY VEHICLES AND ENGINES (CONTINUED) Emission Regulations for Otto-Cycle Heavy-Duty...

Monitoring and Predicting the Export and Fate of Global Ocean Net Primary Production: The EXPORTS Field Program

NASA Astrophysics Data System (ADS)

Exports Science Definition Team

2016-04-01

Ocean ecosystems play a critical role in the Earth's carbon cycle and its quantification on global scales remains one of the greatest challenges in global ocean biogeochemistry. The goal of the EXport Processes in the Ocean from Remote Sensing (EXPORTS) science plan is to develop a predictive understanding of the export and fate of global ocean primary production and its implications for the Earth's carbon cycle in present and future climates. NASA's satellite ocean-color data record has revolutionized our understanding of global marine systems. EXPORTS is designed to advance the utility of NASA ocean color assets to predict how changes in ocean primary production will impact the global carbon cycle. EXPORTS will create a predictive understanding of both the export of organic carbon from the euphotic zone and its fate in the underlying "twilight zone" (depths of 500 m or more) where variable fractions of exported organic carbon are respired back to CO2. Ultimately, it is the sequestration of deep organic carbon transport that defines the impact of ocean biota on atmospheric CO2 levels and hence climate. EXPORTS will generate a new, detailed understanding of ocean carbon transport processes and pathways linking upper ocean phytoplankton processes to the export and fate of organic matter in the underlying twilight zone using a combination of field campaigns, remote sensing and numerical modeling. The overarching objective for EXPORTS is to ensure the success of future satellite missions by establishing mechanistic relationships between remotely sensed signals and carbon cycle processes. Through a process-oriented approach, EXPORTS will foster new insights on ocean carbon cycling that will maximize its societal relevance and be a key component in the U.S. investment to understand Earth as an integrated system.

Testing Urey's carbonate-silicate cycle using the calcium isotopic composition of sedimentary carbonates

NASA Astrophysics Data System (ADS)

Blättler, Clara L.; Higgins, John A.

2017-12-01

Carbonate minerals constitute a major component of the sedimentary geological record and an archive of a fraction of the carbon and calcium cycled through the Earth's surface reservoirs for over three billion years. For calcium, carbonate minerals constitute the ultimate sink for almost all calcium liberated during continental and submarine weathering of silicate minerals. This study presents >500 stable isotope ratios of calcium in Precambrian carbonate sediments, both limestones and dolomites, in an attempt to characterize the isotope mass balance of the sedimentary carbonate reservoir through time. The mean of the dataset is indistinguishable from estimates of the calcium isotope ratio of bulk silicate Earth, consistent with the Urey cycle being the dominant mechanism exchanging calcium among surface reservoirs. The variability in bulk sediment calcium isotope ratios within each geological unit does not reflect changes in the global calcium cycle, but rather highlights the importance of local mineralogical and/or diagenetic effects in the carbonate record. This dataset demonstrates the potential for calcium isotope ratios to help assess these local effects, such as the former presence of aragonite, even in rocks with a history of neomorphism and recrystallization. Additionally, 29 calcium isotope measurements are presented from ODP (Ocean Drilling Program) Site 801 that contribute to the characterization of altered oceanic crust as an additional sink for calcium, and whose distinct isotopic signature places a limit on the importance of this subduction flux over Earth history.

Composite materials for space applications

NASA Technical Reports Server (NTRS)

Rawal, Suraj P.; Misra, Mohan S.; Wendt, Robert G.

1990-01-01

The objectives of the program were to: generate mechanical, thermal, and physical property test data for as-fabricated advanced materials; design and fabricate an accelerated thermal cycling chamber; and determine the effect of thermal cycling on thermomechanical properties and dimensional stability of composites. In the current program, extensive mechanical and thermophysical property tests of various organic matrix, metal matrix, glass matrix, and carbon-carbon composites were conducted, and a reliable database was constructed for spacecraft material selection. Material property results for the majority of the as-fabricated composites were consistent with the predicted values, providing a measure of consolidation integrity attained during fabrication. To determine the effect of thermal cycling on mechanical properties, microcracking, and thermal expansion behavior, approximately 500 composite specimens were exposed to 10,000 cycles between -150 and +150 F. These specimens were placed in a large (18 cu ft work space) thermal cycling chamber that was specially designed and fabricated to simulate one year low earth orbital (LEO) thermal cycling in 20 days. With this rate of thermal cycling, this is the largest thermal cycling unit in the country. Material property measurements of the thermal cycled organic matrix composite laminate specimens exhibited less than 24 percent decrease in strength, whereas, the remaining materials exhibited less than 8 percent decrease in strength. The thermal expansion response of each of the thermal cycled specimens revealed significant reduction in hysteresis and residual strain, and the average CTE values were close to the predicted values.

Evaluating climatic response to external radiative forcing during the late Miocene to early Pliocene: New perspectives from eastern equatorial Pacific (IODP U1338) and North Atlantic (ODP 982) locations

NASA Astrophysics Data System (ADS)

Drury, Anna Joy; John, Cédric M.; Shevenell, Amelia E.

2016-01-01

Orbital-scale climate variability during the latest Miocene-early Pliocene is poorly understood due to a lack of high-resolution records spanning 8.0-3.5 Ma, which resolve all orbital cycles. Assessing this variability improves understanding of how Earth's system sensitivity to insolation evolves and provides insight into the factors driving the Messinian Salinity Crisis (MSC) and the Late Miocene Carbon Isotope Shift (LMCIS). New high-resolution benthic foraminiferal Cibicidoides mundulus δ18O and δ13C records from equatorial Pacific International Ocean Drilling Program Site U1338 are correlated to North Atlantic Ocean Drilling Program Site 982 to obtain a global perspective. Four long-term benthic δ18O variations are identified: the Tortonian-Messinian, Miocene-Pliocene, and Early-Pliocene Oxygen Isotope Lows (8-7, 5.9-4.9, and 4.8-3.5 Ma) and the Messinian Oxygen Isotope High (MOH; 7-5.9 Ma). Obliquity-paced variability dominates throughout, except during the MOH. Eleven new orbital-scale isotopic stages are identified between 7.4 and 7.1 Ma. Cryosphere and carbon cycle sensitivities, estimated from δ18O and δ13C variability, suggest a weak cryosphere-carbon cycle coupling. The MSC termination coincided with moderate cryosphere sensitivity and reduced global ice sheets. The LMCIS coincided with reduced carbon cycle sensitivity, suggesting a driving force independent of insolation changes. The response of the cryosphere and carbon cycle to obliquity forcing is established, defined as Earth System Response (ESR). Observations reveal that two late Miocene-early Pliocene climate states existed. The first is a prevailing dynamic state with moderate ESR and obliquity-driven Antarctic ice variations, associated with reduced global ice volumes. The second is a stable state, which occurred during the MOH, with reduced ESR and lower obliquity-driven variability, associated with expanded global ice volumes.

Evolution of organic carbon burial in the Global Ocean during the Neogene

NASA Astrophysics Data System (ADS)

LI, Z.; Zhang, Y.

2017-12-01

Although only a small fraction of the organic carbon (OC) that rains from surface waters is eventually buried in the sediments, it is a process that controls the organic sub-cycle of the long-term carbon cycle, and the key for atmospheric O2, CO2 and nutrient cycling. Here we constrain the spatiotemporal variability of OC burial by quantifying the total organic carbon (TOC) mass accumulation rate (MAR) over the Neogene (23.0-2.6 Ma) by compiling the TOC, age model and sediment density data from sites retrieved by the Deep Sea Drilling Program, Ocean Drilling Program, and Integrated Ocean Drilling Program. We screened all available sites which yielded 80 sites with adequate data quality, covering all major ocean basins and sedimentary depositional environments. All age models are updated to the GTS 2012 timescale so the TOC MAR records from different sites are comparable. Preliminary results show a clear early Miocene peak of OC burial in many sites related to high sediment flux which might reflect the orogenic uplift and/or glacier erosion. Places that receive high influx of terrigenous inputs become "hotspots" for Neogene burial of OC. At "open ocean" sites, OC burial seems to be more impacted by marine productivity changes, with a pronounced increase during the middle Miocene "Monterey Formation" and late Miocene - early Pliocene "Biogenic Bloom". Upon the completion of the data collection, we will further explore the regional and global OC burial in the context of tectonic uplift, climate change and the evolution of primary producers and consumers during the last 23 million years of Earth history.

Fate and Transport of Nitrogen and Carbon with Decomposition of Organic Matter in a Reduced Paddy Field Based on a Coupled Nitrogen-Carbon Cycling Model Using the HP1 Code

NASA Astrophysics Data System (ADS)

Toride, N.; Matsuoka, K.

2017-12-01

In order to predict the fate and transport of nitrogen in a reduced paddy field as a result of decomposition of organic matter, we implemented within the PHREEQC program a modified coupled carbon and nitrogen cycling model based on the LEACHM code. SOM decay processes from organic carbon (Org-C) to biomass carbon (Bio-C), humus carbon (Hum-C), and carbon dioxide (CO2) were described using first-order kinetics. Bio-C was recycled into the organic pool. When oxygen was available in an aerobic condition, O2 was used to produce CO2 as an electron accepter. When O2 availability is low, other electron acceptors such as NO3-, Mn4+, Fe3+, SO42-, were used depending on the redox potential. Decomposition of Org-N was related to the carbon cycle using the C/N ratio. Mineralization and immobilization were determined based on available NH4-N and the nitrogen demand for the formation of biomass and humus. Although nitrification was independently described with the first-order decay process, denitrification was linked with the SOM decay since NO3- was an electron accepter for the CO2 production. Proton reactions were coupled with the nitrification from NH4+ to NO3-, and the ammonium generation from NH3 to NH4+. Furthermore, cation and anion exchange reactions were included with the permanent negative charges and the pH dependent variable charges. The carbon and nitrogen cycling model described with PHREEQC was linked with HYDRUS-1D using the HP1 code. Various nitrogen and carbon transport scenarios were demonstrated for the application of organic matter to a saturated paddy soil.

Advancing Ocean Science Through Coordination, Community Building, and Outreach

NASA Astrophysics Data System (ADS)

Benway, H. M.

2016-02-01

The US Ocean Carbon and Biogeochemistry (OCB) Program (www.us-ocb.org) is a dynamic network of scientists working across disciplines to understand the ocean's role in the global carbon cycle and how marine ecosystems and biogeochemical cycles are responding to environmental change. The OCB Project Office, which is based at the Woods Hole Oceanographic Institution (WHOI), serves as a central information hub for this network, bringing different scientific disciplines together and cultivating partnerships with complementary US and international programs to address high-priority research questions. The OCB Project Office plays multiple important support roles, such as hosting and co-sponsoring workshops, short courses, working groups, and synthesis activities on emerging research issues; engaging with relevant national and international science planning initiatives; and developing education and outreach activities and products with the goal of promoting ocean carbon science to broader audiences. Current scientific focus areas of OCB include ocean observations (shipboard, autonomous, satellite, etc.); changing ocean chemistry (acidification, expanding low-oxygen conditions, etc.); ocean carbon uptake and storage; estuarine and coastal carbon cycling; biological pump and associated biological and biogeochemical processes and carbon fluxes; and marine ecosystem response to environmental and evolutionary changes, including physiological and molecular-level responses of individual organisms, as well as shifts in community structure and function. OCB is a bottom-up organization that responds to the continually evolving priorities and needs of its network and engages marine scientists at all career stages. The scientific leadership of OCB includes a scientific steering committee and subcommittees on ocean time-series, ocean acidification, and ocean fertilization. This presentation will highlight recent OCB activities and products of interest to the ocean science community.

Aligning ecology and markets in the forest carbon cycle

Treesearch

Matthew D. Hurteau; Bruce A. Hungate; George W. Koch; Malcolm P. North; Gordon R Smith

2013-01-01

A forest carbon (C) offset is a quantifiable unit of C that is commonly developed at the local or regional project scale and is designed to counterbalance anthropogenic C emissions by sequestering C in trees. In capand- trade programs, forest offsets have market value if the sequestered C is additional (more than would have occurred in the absence of the project) and...

The CARIACO Ocean Time-Series: two decades of oceanographic observations to understand linkages between biogeochemistry, ecology, and long-term environmental variability.

NASA Astrophysics Data System (ADS)

Lorenzoni, L.; Muller-Karger, F. E.; Rueda-Roa, D. T.; Thunell, R.; Scranton, M. I.; Taylor, G. T.; benitez-Nelson, C. R.; Montes, E.; Astor, Y. M.; Rojas, J.

2016-02-01

The CARIACO Ocean Time-Series project, located in the Cariaco Basin off the coast of Venezuela, seeks to understand relationships between hydrography, primary production, community composition, microbial activity, particle fluxes, and element cycling in the water column, and how variations in these processes are preserved in sediments accumulating in this anoxic basin. CARIACO uses autonomous and shipboard measurements to understand ecological and biogeochemical changes and how these relate to regional and global climatic/ocean variability. CARIACO is a model for national ocean observing programs in Central/South America, and has been developed as a community facility platform with open access to all data (http://imars.marine.usf.edu/cariaco). Research resulting from this program has contributed to knowledge about the decomposition and cycling of particles, the biological pump, and to our understanding of the ecology and oceanography of oxygen minimum zones. Despite this basin being anoxic below 250m, remineralization rates of organic matter are comparable to those in well oxygenated waters. A dynamic microbial community significantly influences carbon and nutrient biogeochemical cycling throughout the water column. Since 1995, declining particulate organic carbon fluxes have been measured throughout the water column using sediment traps, likely in response to declining Chl-a concentrations and smaller phytoplankton which have replaced the larger taxa over the past decade. This community shift appears to be caused by regional changes in the physical regime. CARIACO also recorded marked long-term changes in surface and deep DIC in response to a combination of factors including surface water warming. The observations of CARIACO highlight the importance of a sustained, holistic approach to studying biodiversity, ecology and the marine carbon cycle to predict potential impacts of climate change on the ocean's ecosystem services and carbon sequestration efficiency.

Designing Catalytic Monoliths For Closed-Cycle CO2 Lasers

NASA Technical Reports Server (NTRS)

Guinn, Keith; Herz, Richard K.; Goldblum, Seth; Noskowski, ED

1992-01-01

LASCAT (Design of Catalytic Monoliths for Closed-Cycle Carbon Dioxide Lasers) computer program aids in design of catalyst in monolith by simulating effects of design decisions on performance of laser. Provides opportunity for designer to explore tradeoffs among activity and dimensions of catalyst, dimensions of monolith, pressure drop caused by flow of gas through monolith, conversion of oxygen, and other variables. Written in FORTRAN 77.

Characterizing the performance of ecosystem models across time scales: A spectral analysis of the North American Carbon Program site-level synthesis

Treesearch

Michael C. Dietze; Rodrigo Vargas; Andrew D. Richardson; Paul C. Stoy; Alan G. Barr; Ryan S. Anderson; M. Altaf Arain; Ian T. Baker; T. Andrew Black; Jing M. Chen; Philippe Ciais; Lawrence B. Flanagan; Christopher M. Gough; Robert F. Grant; David Hollinger; R. Cesar Izaurralde; Christopher J. Kucharik; Peter Lafleur; Shugang Liu; Erandathie Lokupitiya; Yiqi Luo; J. William Munger; Changhui Peng; Benjamin Poulter; David T. Price; Daniel M. Ricciuto; William J. Riley; Alok Kumar Sahoo; Kevin Schaefer; Andrew E. Suyker; Hanqin Tian; Christina Tonitto; Hans Verbeeck; Shashi B. Verma; Weifeng Wang; Ensheng Weng

2011-01-01

Ecosystem models are important tools for diagnosing the carbon cycle and projecting its behavior across space and time. Despite the fact that ecosystems respond to drivers at multiple time scales, most assessments of model performance do not discriminate different time scales. Spectral methods, such as wavelet analyses, present an alternative approach that enables the...

[Modeling of carbon cycling in terrestrial ecosystem: a review].

PubMed

Mao, Liuxi; Sun, Yanling; Yan, Xiaodong

2006-11-01

Terrestrial carbon cycling is one of the important issues in global change research, while carbon cycling modeling has become a necessary method and tool in understanding this cycling. This paper reviewed the research progress in terrestrial carbon cycling, with the focus on the basic framework of simulation modeling, two essential models of carbon cycling, and the classes of terrestrial carbon cycling modeling, and analyzed the present situation of terrestrial carbon cycling modeling. It was pointed out that the future research direction could be based on the biophysical modeling of dynamic vegetation, and this modeling could be an important component in the earth system modeling.

Using CarbonTracker carbon flux estimates to improve a terrestrial carbon cycle model

NASA Astrophysics Data System (ADS)

Peters, W.; Krol, M.; Miller, J. B.; Tans, P. P.; Carvalhais, N.; Schaefer, K.

2009-12-01

Estimates of net ecosystem exchange (NEE) from NOAA’s CarbonTracker CO2 data assimilation system show patterns of annual net uptake not represented in most terrestrial carbon cycle models. This is mainly because such models lack information on the land-use history of individual ecosystems, which is the main driver of long-term mean carbon exchange. Instead, they assume the biosphere to be in steady-state, with annual gross photosynthesis equalling ecosystem respiration everywhere. This limits their use in interpreting observations of carbon dynamics such as with eddy-covariance techniques or through atmospheric CO2 records. We have implemented a method that takes the long-term mean NEE estimates from CarbonTracker to derive the size of the dominant carbon pool in each ecosystem of the SIBCASA biosphere model. With the new pool sizes, the SIBCASA model is no longer in steady-state and reproduces annual carbon uptake patterns from CarbonTracker. We will show that the non steady-state SIBCASA model is not only much more consistent with the atmospheric CO2 record, but also with independent data on standing wood biomass and forest age from the Forest Inventory and Analysis (FIA) Program of the U.S. Forest Service. Four years of CarbonTracker NEE are needed to reliably derive a long term mean for this process, and we use three other years from CarbonTracker to evaluate the non steady state SIBCASA NEE. We will furthermore show that the non steady-state SIBCASA NEE is a much better first-guess for the CarbonTracker data assimilation process, allowing more confidence in its final NEE estimate, and reducing a systematic bias in CarbonTracker modeled atmospheric CO2. This overcomes a long standing issue in inverse modeling, and opens the way for further assessment and improvement of carbon cycle models such as SIBCASA.

Comparing Product Category Rules from Different Programs: Learned Outcomes Towards Global Alignment

EPA Science Inventory

Purpose Product category rules (PCRs) provide category-specific guidance for estimating and reporting product life cycle environmental impacts, typically in the form of environmental product declarations and product carbon footprints. Lack of global harmonization between PCRs or ...

40 CFR 86.090-2 - Definitions.

Code of Federal Regulations, 2012 CFR

2012-07-01

... chamber. Total hydrocarbon equivalent means the sum of the carbon mass emissions of non-oxygenated... Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) CONTROL OF... operating characteristics significantly similar to the theoretical Diesel combustion cycle. The non-use of a...

40 CFR 86.090-2 - Definitions.

Code of Federal Regulations, 2014 CFR

2014-07-01

... chamber. Total hydrocarbon equivalent means the sum of the carbon mass emissions of non-oxygenated... Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) CONTROL OF... operating characteristics significantly similar to the theoretical Diesel combustion cycle. The non-use of a...

40 CFR 86.090-2 - Definitions.

Code of Federal Regulations, 2013 CFR

2013-07-01

... chamber. Total hydrocarbon equivalent means the sum of the carbon mass emissions of non-oxygenated... Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) CONTROL OF... operating characteristics significantly similar to the theoretical Diesel combustion cycle. The non-use of a...

The contribution of China's Grain to Green Programto carbon and water cycles

NASA Astrophysics Data System (ADS)

Yuan, W.

2017-12-01

The Chinese government started implementation of the Grain for Green Project (GGP) in 1999, aiming to convert cropland to forestland to mitigate soil erosion problems in areas across the country. Although the project has generated substantial environmental benefits, such as erosion reduction, carbon sequestration and water quality improvements, the magnitude of these benefits has not yet been well quantified due to the lack of location specific data describing the afforestation efforts. Remote sensing is well suited to detect afforestation locations, a prerequisite for estimating the impacts of the project on carbon and water cycles. In this study, we first examined the practicability of using the Moderate Resolution Imaging Spectroradiometer (MODIS) land cover product to detect afforestation locations; however, the results showed that the MODIS product failed to distinguish the afforestation areas of GGP. Then, we used a normalized difference vegetation index (NDVI) time series analysis approach for detecting afforestation locations, applying statistical data to determine the NDVI threshold of converted croplands. The technique provided the necessary information for location of afforestation implemented under GGP, explaining 85% of conversion from cropland to forestlands across all provinces. Second, we estimated the changes in carbon fluxes and stocks caused by forests converted from croplands under the GGP using a process-based ecosystem model (i.e., IBIS). Our results showed that the converted areas from croplands to forests under the GGP program could sequester 110.45 Tg C by 2020, and 524.36 Tg C by the end of this century. The sequestration capacity showed substantial spatial variations with large sequestration in southern China. The economic benefits of carbon sequestration from the GGP were also estimated according to the current carbon price. The estimated economic benefits ranged from 8.84 to 44.20 billion from 2000 through 2100, which may exceed the current total investment ($38.99 billion) on the program. As the GGP program continues and forests grow, the impact of this program will be even larger in the future, making a more considerable contribution to China's carbon sink over the upcoming decades.

Switching of metabolic programs in response to light availability is an essential function of the cyanobacterial circadian output pathway

PubMed Central

Puszynska, Anna M; O'Shea, Erin K

2017-01-01

The transcription factor RpaA is the master regulator of circadian transcription in cyanobacteria, driving genome-wide oscillations in mRNA abundance. Deletion of rpaA has no effect on viability in constant light conditions, but renders cells inviable in cycling conditions when light and dark periods alternate. We investigated the mechanisms underlying this viability defect, and demonstrate that the rpaA- strain cannot maintain appropriate energy status at night, does not accumulate carbon reserves during the day, and is defective in transcription of genes crucial for utilization of carbohydrate stores at night. Reconstruction of carbon utilization pathways combined with provision of an external carbon source restores energy charge and viability of the rpaA- strain in light/dark cycling conditions. Our observations highlight how a circadian output pathway controls and temporally coordinates essential pathways in carbon metabolism to maximize fitness of cells facing periodic energy limitations. DOI: http://dx.doi.org/10.7554/eLife.23210.001 PMID:28430105

Comparing Product Category Rules from Different Programs: Learned Outcomes Towards Global Alignment (Presentation)

EPA Science Inventory

Purpose Product category rules (PCRs) provide category-specific guidance for estimating and reporting product life cycle environmental impacts, typically in the form of environmental product declarations and product carbon footprints. Lack of global harmonization between PCRs or ...

Ecosystem Model Performance at Wetlands: Results from the North American Carbon Program Site Synthesis

NASA Astrophysics Data System (ADS)

Sulman, B. N.; Desai, A. R.; Schroeder, N. M.; NACP Site Synthesis Participants

2011-12-01

Northern peatlands contain a significant fraction of the global carbon pool, and their responses to hydrological change are likely to be important factors in future carbon cycle-climate feedbacks. Global-scale carbon cycle modeling studies typically use general ecosystem models with coarse spatial resolution, often without peatland-specific processes. Here, seven ecosystem models were used to simulate CO2 fluxes at three field sites in Canada and the northern United States, including two nutrient-rich fens and one nutrient-poor, sphagnum-dominated bog, from 2002-2006. Flux residuals (simulated - observed) were positively correlated with measured water table for both gross ecosystem productivity (GEP) and ecosystem respiration (ER) at the two fen sites for all models, and were positively correlated with water table at the bog site for the majority of models. Modeled diurnal cycles at fen sites agreed well with eddy covariance measurements overall. Eddy covariance GEP and ER were higher during dry periods than during wet periods, while model results predicted either the opposite relationship or no significant difference. At the bog site, eddy covariance GEP had no significant dependence on water table, while models predicted higher GEP during wet periods. All models significantly over-estimated GEP at the bog site, and all but one over-estimated ER at the bog site. Carbon cycle models in peatland-rich regions could be improved by incorporating better models or measurements of hydrology and by inhibiting GEP and ER rates under saturated conditions. Bogs and fens likely require distinct treatments in ecosystem models due to differences in nutrients, peat properties, and plant communities.

Quantifying the Impact of Mountain Pine Beetle Disturbances on Forest Carbon Pools and Fluxes in the Western US using the NCAR Community Land Model

NASA Astrophysics Data System (ADS)

Edburg, S. L.; Hicke, J. A.; Lawrence, D. M.; Thornton, P. E.

2009-12-01

Forest disturbances, such as fire, insects, and land-use change, significantly alter carbon budgets by changing carbon pools and fluxes. The mountain pine beetle (MPB) kills millions of hectares of trees in the western US, similar to the area killed by fire. Mountain pine beetles kill host trees by consuming the inner bark tissue, and require host tree death for reproduction. Despite being a significant disturbance to forested ecosystems, insects such as MPB are typically not represented in biogeochemical models, thus little is known about their impact on the carbon cycle. We investigate the role of past MPB outbreaks on carbon cycling in the western US using the NCAR Community Land Model with Carbon and Nitrogen cycles (CLM-CN). CLM-CN serves as the land model to the Community Climate System Model (CCSM), providing exchanges of energy, momentum, water, carbon, and nitrogen between the land and atmosphere. We run CLM-CN over the western US extending to eastern Colorado with a spatial resolution of 0.5° and a half hour time step. The model is first spun-up with repeated NCEP forcing (1948-1972) until carbon stocks and fluxes reach equilibrium (~ 3000 years), and then run from 1850 to 2004 with NCEP forcing and a dynamic plant functional type (PFT) database. Carbon stocks from this simulation are compared with stocks from the Forest Inventory Analysis (FIA) program. We prescribe MPB mortality area, once per year, in CLM-CN using USFS Aerial Detection Surveys (ADS) from the last few decades. We simulate carbon impacts of tree mortality by MPB within a model grid cell by moving carbon from live vegetative pools (leaf, stem, and roots) to dead pools (woody debris, litter, and dead roots). We compare carbon pools and fluxes for two simulations, one without MPB outbreaks and one with MPB outbreaks.

Coupling a Supercritical Carbon Dioxide Brayton Cycle to a Helium-Cooled Reactor.

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

Middleton, Bobby; Pasch, James Jay; Kruizenga, Alan Michael

2016-01-01

This report outlines the thermodynamics of a supercritical carbon dioxide (sCO 2) recompression closed Brayton cycle (RCBC) coupled to a Helium-cooled nuclear reactor. The baseline reactor design for the study is the AREVA High Temperature Gas-Cooled Reactor (HTGR). Using the AREVA HTGR nominal operating parameters, an initial thermodynamic study was performed using Sandia's deterministic RCBC analysis program. Utilizing the output of the RCBC thermodynamic analysis, preliminary values of reactor power and of Helium flow rate through the reactor were calculated in Sandia's HelCO 2 code. Some research regarding materials requirements was then conducted to determine aspects of corrosion related tomore » both Helium and to sCO 2 , as well as some mechanical considerations for pressures and temperatures that will be seen by the piping and other components. This analysis resulted in a list of materials-related research items that need to be conducted in the future. A short assessment of dry heat rejection advantages of sCO 2> Brayton cycles was also included. This assessment lists some items that should be investigated in the future to better understand how sCO 2 Brayton cycles and nuclear can maximally contribute to optimizing the water efficiency of carbon free power generation« less

An introduction to global carbon cycle management

USGS Publications Warehouse

Sundquist, Eric T.; Ackerman, Katherine V.; Parker, Lauren; Huntzinger, Deborah N.

2009-01-01

Past and current human activities have fundamentally altered the global carbon cycle. Potential future efforts to control atmospheric CO2 will also involve significant changes in the global carbon cycle. Carbon cycle scientists and engineers now face not only the difficulties of recording and understanding past and present changes but also the challenge of providing information and tools for new management strategies that are responsive to societal needs. The challenge is nothing less than managing the global carbon cycle.

The long-term carbon cycle, fossil fuels and atmospheric composition.

PubMed

Berner, Robert A

2003-11-20

The long-term carbon cycle operates over millions of years and involves the exchange of carbon between rocks and the Earth's surface. There are many complex feedback pathways between carbon burial, nutrient cycling, atmospheric carbon dioxide and oxygen, and climate. New calculations of carbon fluxes during the Phanerozoic eon (the past 550 million years) illustrate how the long-term carbon cycle has affected the burial of organic matter and fossil-fuel formation, as well as the evolution of atmospheric composition.

Solar Fuels and Carbon Cycle 2.0 (Carbon Cycle 2.0)

ScienceCinema

Alivisatos, Paul

2018-05-08

Paul Alivisatos, LBNL Director speaks at the Carbon Cycle 2.0 kick-off symposium Feb. 4, 2010. We emit more carbon into the atmosphere than natural processes are able to remove - an imbalance with negative consequences. Carbon Cycle 2.0 is a Berkeley Lab initiative to provide the science needed to restore this balance by integrating the Labs diverse research activities and delivering creative solutions toward a carbon-neutral energy future.

Analytically tractable climate-carbon cycle feedbacks under 21st century anthropogenic forcing

NASA Astrophysics Data System (ADS)

Lade, Steven J.; Donges, Jonathan F.; Fetzer, Ingo; Anderies, John M.; Beer, Christian; Cornell, Sarah E.; Gasser, Thomas; Norberg, Jon; Richardson, Katherine; Rockström, Johan; Steffen, Will

2018-05-01

Changes to climate-carbon cycle feedbacks may significantly affect the Earth system's response to greenhouse gas emissions. These feedbacks are usually analysed from numerical output of complex and arguably opaque Earth system models. Here, we construct a stylised global climate-carbon cycle model, test its output against comprehensive Earth system models, and investigate the strengths of its climate-carbon cycle feedbacks analytically. The analytical expressions we obtain aid understanding of carbon cycle feedbacks and the operation of the carbon cycle. Specific results include that different feedback formalisms measure fundamentally the same climate-carbon cycle processes; temperature dependence of the solubility pump, biological pump, and CO2 solubility all contribute approximately equally to the ocean climate-carbon feedback; and concentration-carbon feedbacks may be more sensitive to future climate change than climate-carbon feedbacks. Simple models such as that developed here also provide workbenches for simple but mechanistically based explorations of Earth system processes, such as interactions and feedbacks between the planetary boundaries, that are currently too uncertain to be included in comprehensive Earth system models.

Simulation of groundwater flow and evaluation of carbon sink in Lijiang Rivershed, China

NASA Astrophysics Data System (ADS)

Hu, Bill X.; Cao, Jianhua; Tong, Juxiu; Gao, Bing

2016-04-01

It is important to study water and carbon cycle processes for water resource management, pollution prevention and global warming influence on southwest karst region of China. Lijiang river basin is selected as our study region. Interdisciplinary field and laboratory experiments with various technologies are conducted to characterize the karst aquifers in detail. Key processes in the karst water cycle and carbon cycle are determined. Based on the MODFLOW-CFP model, new watershed flow and carbon cycle models are developed coupled subsurface and surface water flow models, flow and chemical/biological models. Our study is focused on the karst springshed in Mao village. The mechanisms coupling carbon cycle and water cycle are explored. Parallel computing technology is used to construct the numerical model for the carbon cycle and water cycle in the small scale watershed, which are calibrated and verified by field observations. The developed coupling model for the small scale watershed is extended to a large scale watershed considering the scale effect of model parameters and proper model structure simplification. The large scale watershed model is used to study water cycle and carbon cycle in Lijiang rivershed, and to calculate the carbon flux and carbon sinks in the Lijiang river basin. The study results provide scientific methods for water resources management and environmental protection in southwest karst region corresponding to global climate change. This study could provide basic theory and simulation method for geological carbon sequestration in China karst region.

40 CFR 86.1867-12 - Optional early CO2 credit programs.

Code of Federal Regulations, 2010 CFR

2010-07-01

... efficiency credits, early advanced technology credits, and early off-cycle technology credits. Manufacturers...) Carbon-related exhaust emission values for electric, fuel cell, and plug-in hybrid electric model types... extent that such vehicles are not being used to generate early advanced technology vehicle credits under...

Environmental Sciences Division annual progress report for period ending September 30, 1983

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

Not Available

1984-04-01

This annual report summarizes activities in the Aquatic Ecology, Earth Sciences, Environmental Analyses, and Terrestrial Ecology sections, as well as in the Fossil Energy, Biomass, Low-Level Waste Research and Management, and Global Carbon Cycle Programs. Separate abstracts have been prepared for each section. (ACR)

40 CFR 86.1867-12 - Optional early CO2 credit programs.

Code of Federal Regulations, 2012 CFR

2012-07-01

... efficiency credits, early advanced technology credits, and early off-cycle technology credits. Manufacturers... an approved value. (F) Carbon-related exhaust emission values for electric, fuel cell, and plug-in hybrid electric model types shall be included in the fleet average determined under paragraph (a)(1) of...

40 CFR 86.1871-12 - Optional early CO2 credit programs.

Code of Federal Regulations, 2013 CFR

2013-07-01

... efficiency credits, early advanced technology credits, and early off-cycle technology credits. Manufacturers... manufacturer may use such an approved value. (F) Carbon-related exhaust emission values for electric, fuel cell, and plug-in hybrid electric model types shall be included in the fleet average determined under...

40 CFR 86.1867-12 - Optional early CO2 credit programs.

Code of Federal Regulations, 2011 CFR

2011-07-01

... efficiency credits, early advanced technology credits, and early off-cycle technology credits. Manufacturers...) Carbon-related exhaust emission values for electric, fuel cell, and plug-in hybrid electric model types... extent that such vehicles are not being used to generate early advanced technology vehicle credits under...

Understanding user needs for carbon monitoring information

NASA Astrophysics Data System (ADS)

Duren, R. M.; Macauley, M.; Gurney, K. R.; Saatchi, S. S.; Woodall, C. W.; Larsen, K.; Reidmiller, D.; Hockstad, L.; Weitz, M.; Croes, B.; Down, A.; West, T.; Mercury, M.

2015-12-01

The objectives of the Understanding User Needs project for NASA's Carbon Monitoring System (CMS) program are to: 1) engage the user community and identify needs for policy-relevant carbon monitoring information, 2) evaluate current and planned CMS data products with regard to their value for decision making, and 3) explore alternative methods for visualizing and communicating carbon monitoring information and associated uncertainties to decision makers and other stakeholders. To meet these objectives and help establish a sustained link between science and decision-making we have established a multi-disciplinary team that combines expertise in carbon-cycle science, engineering, economics, and carbon management and policy. We will present preliminary findings regarding emerging themes and needs for carbon information that may warrant increased attention by the science community. We will also demonstrate a new web-based tool that offers a common framework for facilitating user evaluation of carbon data products from multiple CMS projects.

Combustion and Carbon Cycle 2.0 and Computation in CC 2.0 (Carbon Cycle 2.0)

ScienceCinema

Cheng, Robert K.; Meza, Juan

2018-05-04

Robert Cheng and Juan Meza provide two presentations in one session at the Carbon Cycle 2.0 kick-off symposium Feb. 3, 2010. We emit more carbon into the atmosphere than natural processes are able to remove - an imbalance with negative consequences. Carbon Cycle 2.0 is a Berkeley Lab initiative to provide the science needed to restore this balance by integrating the Labs diverse research activities and delivering creative solutions toward a carbon-neutral energy future.

A Call to Action: Carbon Cycle 2.0 (Carbon Cycle 2.0)

ScienceCinema

Alivisatos, Paul [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

2018-05-21

Berkeley Lab Director Paul Alivisatos speaks at the Carbon Cycle 2.0 kick-off symposium Feb. 1, 2010. Humanity emits more carbon into the atmosphere than natural processes are able to remove - an imbalance with negative consequences.Carbon Cycle 2.0 is a Berkeley Lab initiative to provide the science needed to restore this balance by integrating the Labs diverse research activities and delivering creative solutions toward a carbon-neutral energy future. http://carboncycle2.lbl.gov/

A Future with (out) Carbon Cycle 2.0 (Carbon Cycle 2.0)

ScienceCinema

Collins, Bill [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

2018-05-21

Bill Collins, Head of LBNL's Climate Sciences Department, speaks at the Carbon Cycle 2.0 kick-off symposium Feb. 1, 2010. We emit more carbon into the atmosphere than natural processes are able to remove - an imbalance with negative consequences. Carbon Cycle 2.0 is a Berkeley Lab initiative to provide the science needed to restore this balance by integrating the Labs diverse research activities and delivering creative solutions toward a carbon-neutral energy future. http://carboncycle2.lbl.gov/

Lithium ion rechargeable systems studies

NASA Astrophysics Data System (ADS)

Levy, Samuel C.; Lasasse, Robert R.; Cygan, Randall T.; Voigt, James A.

Lithium ion systems, although relatively new, have attracted much interest worldwide. Their high energy density, long cycle life and relative safety, compared with metallic lithium rechargeable systems, make them prime candidates for powering portable electronic equipment. Although lithium ion cells are presently used in a few consumer devices, e.g., portable phones, camcorders, and laptop computers, there is room for considerable improvement in their performance. Specific areas that need to be addressed include: (1) carbon anode-increase reversible capacity, and minimize passivation; (2) cathode-extend cycle life, improve rate capability, and increase capacity. There are several programs ongoing at Sandia National Laboratories which are investigating means of achieving the stated objectives in these specific areas. This paper will review these programs.

GeoEthics from the Ground Up: A Carbon-Neutral Education

NASA Astrophysics Data System (ADS)

Moore, A.; Derry, L. A.

2014-12-01

Discussion with students about the science of global warming and the consequences of greenhouse gas emissions - while emitting greenhouse gasses in the process - is a focal point for geoethics in the Cornell University Earth and Environmental Systems (EES) Field Program. If we seek to educate students in the fundamentals of environmental stewardship we must also put stewardship into practice as part of that education. The EES program is a semester length earth systems field program held on Hawai`i Island. In Hawai`i students gain first-hand experience with the interconnected solid earth, living earth, ocean and atmosphere. They also gain first-hand experience with the consequences of unsustainable resource use: marine resource depletion, deforestation and species loss, development v. conservation, fossil fuel v. alternative energy options. Yet as a travel-based field program the pursuit of these goals carries a clear environmental cost. Thus a core element of EES education is to run a carbon-neutral program. To achieve this, students quantify every aspect of the program's carbon footprint. They decide which actions they must include as part of that footprint and learn how to monitor and calculate the resulting CO2 emissions. Students learn how to reduce emissions where possible, and offset emissions that cannot be eliminated. Working in partnership with island-based conservation organizations students engage in reforestation of degraded native forest landscapes. They model the carbon sequestration capacity of restored forest biomass and soil reservoirs. The outcome of this process has triple-bottom-line benefits: (1) native forest and endangered species habitat is restored, (2) carbon dioxide is removed from the atmosphere and sequestered, and (3) students gain hands-on, minds-on experience with carbon-cycle science, ecosystem science, and with the ethical imperative of putting one's knowledge into action.

The Wildland Fire Emissions Information System: Providing information for carbon cycle studies with open source geospatial tools

NASA Astrophysics Data System (ADS)

French, N. H.; Erickson, T.; McKenzie, D.

2008-12-01

A major goal of the North American Carbon Program is to resolve uncertainties in understanding and managing the carbon cycle of North America. As carbon modeling tools become more comprehensive and spatially oriented, accurate datasets to spatially quantify carbon emissions from fire are needed, and these data resources need to be accessible to users for decision-making. Under a new NASA Carbon Cycle Science project, Drs. Nancy French and Tyler Erickson, of the Michigan Technological University, Michigan Tech Research Institute (MTRI), are teaming with specialists with the USDA Forest Service Fire and Environmental Research Applications (FERA) team to provide information for mapping fire-derived carbon emissions to users. The project focus includes development of a web-based system to provide spatially resolved fire emissions estimates for North America in a user-friendly environment. The web-based Decision Support System will be based on a variety of open source technologies. The Fuel Characteristic Classification System (FCCS) raster map of fuels and MODIS-derived burned area vector maps will be processed using the Geographic Data Abstraction Library (GDAL) and OGR Simple Features Library. Tabular and spatial project data will be stored in a PostgreSQL/PostGIS, a spatially enabled relational database server. The browser-based user interface will be created using the Django web page framework to allow user input for the decision support system. The OpenLayers mapping framework will be used to provide users with interactive maps within the browser. In addition, the data products will be made available in standard open data formats such as KML, to allow for easy integration into other spatial models and data systems.

Design of catalytic monoliths for closed-cycle carbon dioxide lasers

NASA Technical Reports Server (NTRS)

Herz, R. K.; Guinn, K.; Goldblum, S.; Noskowski, E.

1989-01-01

Pulsed carbon dioxide (CO2) lasers have many applications in aeronautics, space research, weather monitoring and other areas. Full exploitation of the potential of these lasers in hampered by the dissociation of CO2 that occurs during laser operation. The development of closed-cycle CO2 lasers requires active CO-O2 recombination (CO oxidation) catalyst and design methods for implementation of catalysts in CO2 laser systems. A monolith catalyst section model and associated design computer program, LASCAT, are presented to assist in the design of a monolith catalyst section of a closed cycle CO2 laser system. Using LASCAT,the designer is able to specify a number of system parameters and determine the monolith section performance. Trade-offs between the catalyst activity, catalyst dimensions, monolith dimensions, pressure drop, O2 conversion, and other variables can be explored and adjusted to meet system design specifications. An introduction describes a typical closed-cycle CO2 system, and indicates some advantages of a closed cycle laser system over an open cycle system and some advantages of monolith support over other types of supports. The development and use of a monolith catalyst model is presented. The results of a design study and a discussion of general design rules are given.

Coupling between the continental carbon and water cycles

NASA Astrophysics Data System (ADS)

Gentine, P.; Lemordant, L. A.; Green, J. K.

2017-12-01

The continental carbon adn water cycles are fundamentally coupled through leaf gas exchange at the stomata level. IN this presnetation we will emphasize the importance of this coupling for the future of the water cycle (runoff, evaporation, soil moisture) and in turn the implications for the carbon cycle and the capacity of continents to act as a carbon dioxyde sink in the future. Opprtunites from coupled carbon-water monitoring platforms will be then emphasized.

The Role of Atmospheric Organic Nitrogen in Forest Nitrogen Cycling

NASA Astrophysics Data System (ADS)

Lockwood, A.; Shepson, P.; Rhodes, D.

2003-12-01

Changes in the global climate and atmosphere cause significant effects to the biosphere. Forests respond to these global changes in various ways which all can affect their ability to store carbon, which in turn impacts climate change. Many temperate latitude forests are nitrogen-limited. A current working hypothesis is that atmospheric nitrogen compounds that are deposited to the canopy may be directly utilized by the plant as a nitrogen source. A significant fraction of atmospheric reactive nitrogen that can be deposited is organic. Organic nitrogen deposition is not well characterized nor have the ecological consequences been assessed. Our hypothesis is that organic nitrogen deposition to the canopy is significant, and that that nitrogen is utilized by trees. Fumigation experiments were conducted with 14N and 15N-labeled organic nitrates (focusing on 1-nitrooxy-3-methyl butane as a surrogate for isoprene nitrates) to determine if and how that nitrogen gets incorporated into the leaves by detecting the 15N-labeled leaf amino acids. This research builds on work completed during past summer intensives as part of the Program for Research on Oxidants: PHotochemistry, Emissions, and Transport (PROPHET), and begins the next stage of research as part of the Biosphere Atmosphere Research & Training program (BART) at the University of Michigan Biological Station (UMBS). The overall goal of the new effort, the Biosphere Exchange of Atmospheric Carbon and Odd Nitrogen (BEACON) program, is to evaluate the interactive roles of the atmosphere and forest in the coupling of the carbon and nitrogen cycles.

Society and the Carbon Cycle: A Social Science Perspective

NASA Astrophysics Data System (ADS)

Romero-Lankao, P.

2017-12-01

Societal activities, actions, and practices affect the carbon cycle and the climate of North America in complex ways. Carbon is a key component for the functioning of croplands, grasslands, forests. Carbon fuels our industry, transportation (vehicles and roadways), buildings, and other structures. Drawing on results from the SOCCR-2, this presentation uses a social science perspective to address three scientific questions. How do human actions and activities affect the carbon cycle? How human systems such as cities, agricultural field and forests are affected by changes in the carbon cycle? How is carbon management enabled and constraint by socio-political dynamics?

Effect of mission cycling on the fatigue performance of SiC-coated carbon-carbon composites

NASA Technical Reports Server (NTRS)

Mahfuz, H.; Das, P. S.; Jeelani, S.; Baker, D. M.; Johnson, S. A.

1993-01-01

The effects of thermal and pressure cycling on the fatigue performance of carbon-carbon composites, and the influence of mission cycling on these effects, were investigated by subjecting both virgin and mission-cycled two-dimensional specimens of SiC-coated carbon-carbon composites to fatigue tests, conducted at room temperature in three-point bending, with a stress ratio of 0.2 and a frequency of 1 Hz. It was found that the fatigue strength of C-C composites is high (about 90 percent of the ultimate flexural strength), but decreased with the mission cycling. The lowering of the fatigue strength with mission cycling is attributed to the increase in interfacial bond strength due to thermal and pressure cycling of the material. The already high sensitivity of C-C composites to stress during cyclic loading increases further with the amount of mission cycling. Results of NDE suggest that the damage growth in virgin C-C, in the high-cycle range, is slow at the initial stage of the cyclic life, but propagates rapidly after certain threshold cycles of the fatigue life.

Insights into Paleogene biogeochemistry from coupled carbon and sulfur isotopes in foraminiferal calcite.

NASA Astrophysics Data System (ADS)

Rennie, V.; Paris, G.; Abramovitch, S.; Sessions, A. L.; Adkins, J. F.; Turchyn, A. V.

2014-12-01

The Paleogene witnessed large-scale environmental changes, including the beginning of long-term Cenozoic cooling. The carbon isotope composition of foraminiferal calcite suggests a major reorganization of the carbon cycle over the Paleogene, with enhanced organic carbon burial in the Paleocene, and subsequent oxidation of this organic carbon or increased volcanism throughout the Eocene. The sulfur cycle is linked to the carbon cycle via the breakdown of organic carbon during bacterial sulfate reduction. Over geological time, carbon and sulfur isotopic shifts are often coupled due to enhanced pyrite burial being coupled to enhanced organic carbon burial, and enhanced pyrite weathering being coupled to enhanced organic carbon weathering. However, over the Paleogene, carbon and sulfur isotopes are fully decoupled, with the sulfur isotope record showing only one major shift in the early Eocene, after most of the carbon isotope variability is complete. One complication of interpreting the evolution of the sulfur cycle over the Cenozoic, is the fact that the mineral proxies used (typically barite) may not be temporally coincident with those used to reconstruct the carbon cycle (typically carbonate). Furthermore, these minerals are preserved in different locations, and therefore often must be extracted from different sediment cores in different ocean basins, leading to age-model uncertainty when the records are merged. To properly ascertain the phasing between early Cenozoic changes in the carbon cycle and the sulfur cycle, we would ideally measure all isotope records on the same mineral. A new sulfur isotope analytical technique [1] has been optimised for foraminiferal calcite as a proxy for seawater δ34SSO4. The δ34SSO4 in foraminiferal calcite can then be tied to records of carbon isotopes from stratigraphically identical samples, resolving previous age model uncertainties. We present coupled carbon and sulfur isotope records from the same core over the early-to-mid Eocene, to better resolve the relative timing of changes in the carbon and sulfur cycles. We use a numerical model to explore the environmental changes necessary for the observed evolution in both the carbon and sulfur cycles. [1] Paris et al, 2013 Chemical Geology, 345, 50-61

The GLOBE Carbon Cycle Project: Using a systems approach to understand carbon and the Earth's climate system

NASA Astrophysics Data System (ADS)

Silverberg, S. K.; Ollinger, S. V.; Martin, M. E.; Gengarelly, L. M.; Schloss, A. L.; Bourgeault, J. L.; Randolph, G.; Albrechtova, J.

2009-12-01

National Science Content Standards identify systems as an important unifying concept across the K-12 curriculum. While this standard exists, there is a recognized gap in the ability of students to use a systems thinking approach in their learning. In a similar vein, both popular media as well as some educational curricula move quickly through climate topics to carbon footprint analyses without ever addressing the nature of carbon or the carbon cycle. If students do not gain a concrete understanding of carbon’s role in climate and energy they will not be able to successfully tackle global problems and develop innovative solutions. By participating in the GLOBE Carbon Cycle project, students learn to use a systems thinking approach, while at the same time, gaining a foundation in the carbon cycle and it's relation to climate and energy. Here we present the GLOBE Carbon Cycle project and materials, which incorporate a diverse set of activities geared toward upper middle and high school students with a variety of learning styles. A global carbon cycle adventure story and game let students see the carbon cycle as a complete system, while introducing them to systems thinking concepts including reservoirs, fluxes and equilibrium. Classroom photosynthesis experiments and field measurements of schoolyard vegetation brings the global view to the local level. And the use of computer models at varying levels of complexity (effects on photosynthesis, biomass and carbon storage in global biomes, global carbon cycle) not only reinforces systems concepts and carbon content, but also introduces students to an important scientific tool necessary for understanding climate change.

Karst medium characterization and simulation of groundwater flow in Lijiang Riversed, China

NASA Astrophysics Data System (ADS)

Hu, B. X.

2015-12-01

It is important to study water and carbon cycle processes for water resource management, pollution prevention and global warming influence on southwest karst region of China. Lijiang river basin is selected as our study region. Interdisciplinary field and laboratory experiments with various technologies are conducted to characterize the karst aquifers in detail. Key processes in the karst water cycle and carbon cycle are determined. Based on the MODFLOW-CFP model, new watershed flow and carbon cycle models are developed coupled subsurface and surface water flow models, flow and chemical/biological models. Our study is focused on the karst springshed in Mao village. The mechanisms coupling carbon cycle and water cycle are explored. Parallel computing technology is used to construct the numerical model for the carbon cycle and water cycle in the small scale watershed, which are calibrated and verified by field observations. The developed coupling model for the small scale watershed is extended to a large scale watershed considering the scale effect of model parameters and proper model structure simplification. The large scale watershed model is used to study water cycle and carbon cycle in Lijiang rivershed, and to calculate the carbon flux and carbon sinks in the Lijiang river basin. The study results provide scientific methods for water resources management and environmental protection in southwest karst region corresponding to global climate change. This study could provide basic theory and simulation method for geological carbon sequestration in China karst region.

The 1994 Arctic Ocean Section. The First Major Scientific Crossing of the Arctic Ocean,

DTIC Science & Technology

1996-09-01

contribute to the international effort to better understand the role of the Arctic Ocean in the global carbon cycle and climate change. Summar...Barium Distributions in the Arctic Ocean ? ........................ 32 Biology and the Carbon Cycle Cycling of Organic Carbon in the Central Arctic...of Heterotrophic Bacteria and Protists in the Arctic Ocean Carbon Cycle............. 40

Analysis of Co-spatial UV-Optical STIS Spectra of Six Planetary Nebulae From HST Cycle 19 GO 12600

NASA Astrophysics Data System (ADS)

Reid Miller, Timothy; Henry, Richard B. C.; Dufour, Reginald J.; Kwitter, Karen; Shaw, Richard A.; Balick, Bruce; Corradi, Romano

2015-08-01

We present an analysis of six spatially resolved planetary nebulae (PNe), NGC 3242, NGC 5315, NGC5882, NGC 7662, IC 2165, and IC 3568, from observations in the Cycle 19 program GO 12600 using HSTSTIS. These six observations cover the wavelength range 1150-10,270 Å with 0.2 and 0.5 arcsec wideslits, and are co-spatial to 0.1 arcsec along a 25 arcsec length across each nebula. The wavelength andspatial coverage enabled this detailed study of physical conditions and abundances from UV and opticalline emissions (compared to only optical lines) for these six PNe. The first UV lines of interest are thoseof carbon. The resolved lines of C III] 1906.68 and 1908.73 yielded a direct measurement of the densitywithin the volume occupied by doubly-ionized carbon and other similar co-spatial ions as well ascontributed to an accurate measurement of the carbon abundance. Each PN spectrum was divided intosmaller spatial regions in order to assess inferred density variations among the regions along the entireslit. There is a clear difference in the inferred density for several regions of each PNe. Variations inelectron temperature and chemical abundances were also probed and shown to be nearly completelyhomogeneous within the errors. Lastly, these nebulae were modeled in detail with the photoionizationcode CLOUDY. This modeling tested different density profiles in order to reproduce the observed densityvariations and temperature fluctuations, and constrain central star parameters. We gratefullyacknowledge generous support from NASA through grants related to the Cycle 19 program GO 12600, aswell as from the University of Oklahoma.

Reviews and syntheses: Systematic Earth observations for use in terrestrial carbon cycle data assimilation systems

NASA Astrophysics Data System (ADS)

Scholze, Marko; Buchwitz, Michael; Dorigo, Wouter; Guanter, Luis; Quegan, Shaun

2017-07-01

The global carbon cycle is an important component of the Earth system and it interacts with the hydrology, energy and nutrient cycles as well as ecosystem dynamics. A better understanding of the global carbon cycle is required for improved projections of climate change including corresponding changes in water and food resources and for the verification of measures to reduce anthropogenic greenhouse gas emissions. An improved understanding of the carbon cycle can be achieved by data assimilation systems, which integrate observations relevant to the carbon cycle into coupled carbon, water, energy and nutrient models. Hence, the ingredients for such systems are a carbon cycle model, an algorithm for the assimilation and systematic and well error-characterised observations relevant to the carbon cycle. Relevant observations for assimilation include various in situ measurements in the atmosphere (e.g. concentrations of CO2 and other gases) and on land (e.g. fluxes of carbon water and energy, carbon stocks) as well as remote sensing observations (e.g. atmospheric composition, vegetation and surface properties).We briefly review the different existing data assimilation techniques and contrast them to model benchmarking and evaluation efforts (which also rely on observations). A common requirement for all assimilation techniques is a full description of the observational data properties. Uncertainty estimates of the observations are as important as the observations themselves because they similarly determine the outcome of such assimilation systems. Hence, this article reviews the requirements of data assimilation systems on observations and provides a non-exhaustive overview of current observations and their uncertainties for use in terrestrial carbon cycle data assimilation. We report on progress since the review of model-data synthesis in terrestrial carbon observations by Raupach et al.(2005), emphasising the rapid advance in relevant space-based observations.

Simulated Effect of Carbon Cycle Feedback on Climate Response to Solar Geoengineering

NASA Astrophysics Data System (ADS)

Cao, Long; Jiang, Jiu

2017-12-01

Most modeling studies investigate climate effects of solar geoengineering under prescribed atmospheric CO2, thereby neglecting potential climate feedbacks from the carbon cycle. Here we use an Earth system model to investigate interactive feedbacks between solar geoengineering, global carbon cycle, and climate change. We design idealized sunshade geoengineering simulations to prevent global warming from exceeding 2°C above preindustrial under a CO2 emission scenario with emission mitigation starting from middle of century. By year 2100, solar geoengineering reduces the burden of atmospheric CO2 by 47 PgC with enhanced carbon storage in the terrestrial biosphere. As a result of reduced atmospheric CO2, consideration of the carbon cycle feedback reduces required insolation reduction in 2100 from 2.0 to 1.7 W m-2. With higher climate sensitivity the effect from carbon cycle feedback becomes more important. Our study demonstrates the importance of carbon cycle feedback in climate response to solar geoengineering.

Carbon Capture (Carbon Cycle 2.0)

ScienceCinema

Smit, Berend

2018-04-26

Berend Smit speaks at the Carbon Cycle 2.0 kick-off symposium Feb. 3, 2010. We emit more carbon into the atmosphere than natural processes are able to remove - an imbalance with negative consequences. Carbon Cycle 2.0 is a Berkeley Lab initiative to provide the science needed to restore this balance by integrating the labs diverse research activities and delivering creative solutions toward a carbon-neutral energy future.

Field Investigation and Modeling Development for Hydrological and Carbon Cycles in Southwest Karst Region of China

NASA Astrophysics Data System (ADS)

Hu, X. B.

2017-12-01

It is required to understanding water cycle and carbon cycle processes for water resource management and pollution prevention and global warming influence in southwest karst region of China. Lijiang river basin is selected as our study region. Interdisciplinary field and laboratory experiments with various technologies are conducted to characterize the karst aquifers in detail. Key processes in the karst water cycle and carbon cycle are determined. Based on the MODFLOW-CFP model, new watershed flow and carbon cycle models are developed coupled subsurface and surface water flow models. Our study focus on the karst springshed in Mao village, the mechanisms coupling carbon cycle and water cycle are explored. This study provides basic theory and simulation method for water resource management and groundwater pollution prevention in China karst region.

Assessing Students' Disciplinary and Interdisciplinary Understanding of Global Carbon Cycling

ERIC Educational Resources Information Center

You, Hye Sun; Marshall, Jill A.; Delgado, Cesar

2018-01-01

Global carbon cycling describes the movement of carbon through atmosphere, biosphere, geosphere, and hydrosphere; it lies at the heart of climate change and sustainability. To understand the global carbon cycle, students will require "interdisciplinary knowledge." While standards documents in science education have long promoted…

40 CFR 600.514-12 - Reports to the Environmental Protection Agency.

Code of Federal Regulations, 2012 CFR

2012-07-01

...-cycle technology, and various early credit programs; (vi) A description of the method which will be used to calculate the carbon-related exhaust emissions for any electric vehicles, fuel cell vehicles and... number of electric vehicles, fuel cell vehicles and plug-in hybrid vehicles using (or projected to use...

[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 in low-carbon transport.

Carbon Goes To…

ERIC Educational Resources Information Center

Savasci, Funda

2014-01-01

The purposes of this activity are to help middle school students understand the carbon cycle and realize how human activities affect the carbon cycle. This activity consists of two parts. The first part of the activity focuses on the carbon cycle, especially before the Industrial Revolution, while the second part of the activity focuses on how…

40 CFR Table 3 to Subpart Mmm of... - Monitoring Requirements for Control Devices a

Code of Federal Regulations, 2012 CFR

2012-07-01

.... Carbon adsorber (regenerative) Stream flow monitoring device, and 1. Total regeneration stream mass or volumetric flow during carbon bed regeneration cycle(s) 1. For each regeneration cycle, record the total regeneration stream mass or volumetric flow. Carbon bed temperature monitoring device 2. Temperature of carbon...

40 CFR Table 3 to Subpart Mmm of... - Monitoring Requirements for Control Devices a

Code of Federal Regulations, 2011 CFR

2011-07-01

.... Carbon adsorber (regenerative) Stream flow monitoring device, and 1. Total regeneration stream mass or volumetric flow during carbon bed regeneration cycle(s) 1. For each regeneration cycle, record the total regeneration stream mass or volumetric flow. Carbon bed temperature monitoring device 2. Temperature of carbon...

40 CFR Table 3 to Subpart Mmm of... - Monitoring Requirements for Control Devices a

Code of Federal Regulations, 2010 CFR

2010-07-01

.... Carbon adsorber (regenerative) Stream flow monitoring device, and 1. Total regeneration stream mass or volumetric flow during carbon bed regeneration cycle(s) 1. For each regeneration cycle, record the total regeneration stream mass or volumetric flow. Carbon bed temperature monitoring device 2. Temperature of carbon...

Global Ocean Carbon and Biogeochemistry Coordination

NASA Astrophysics Data System (ADS)

Telszewski, Maciej; Tanhua, Toste; Palacz, Artur

2016-04-01

The complexity of the marine carbon cycle and its numerous connections to carbon's atmospheric and terrestrial pathways means that a wide range of approaches have to be used in order to establish it's qualitative and quantitative role in the global climate system. Ocean carbon and biogeochemistry research, observations, and modelling are conducted at national, regional, and global levels to quantify the global ocean uptake of atmospheric CO2 and to understand controls of this process, the variability of uptake and vulnerability of carbon fluxes into the ocean. These science activities require support by a sustained, international effort that provides a central communication forum and coordination services to facilitate the compatibility and comparability of results from individual efforts and development of the ocean carbon data products that can be integrated with the terrestrial, atmospheric and human dimensions components of the global carbon cycle. The International Ocean Carbon Coordination Project (IOCCP) was created in 2005 by the IOC of UNESCO and the Scientific Committee on Oceanic Research. IOCCP provides an international, program-independent forum for global coordination of ocean carbon and biogeochemistry observations and integration with global carbon cycle science programs. The IOCCP coordinates an ever-increasing set of observations-related activities in the following domains: underway observations of biogeochemical water properties, ocean interior observations, ship-based time-series observations, large-scale ocean acidification monitoring, inorganic nutrients observations, biogeochemical instruments and autonomous sensors and data and information creation. Our contribution is through the facilitation of the development of globally acceptable strategies, methodologies, practices and standards homogenizing efforts of the research community and scientific advisory groups as well as integrating the ocean biogeochemistry observations with the multidisciplinary global ocean observing system. Over the past 4-5 years IOCCP's long standing experience in coordinating biogeochemical observations and data flows globally, resulted in assuming a leadership role during the design and implementation of the biogeochemistry portion of the Framework for Ocean Observing (FOO, 2012). To optimize and enhance the global ocean observing system IOCCP started to implement major elements of the system's approach outlined in the FOO. Starting by setting of ocean observing requirements representing the needs of societal and scientific stakeholders, followed by development of a set of essential ocean variables (EOVs) with spatial and temporal resolution specifications to best meet current demands for data and information services given current and potential national capabilities. The IOCCP works directly with projects and programs programmatically connected to GOOS as well as the WMO-IOC JCOMM to integrate ocean carbon and biogeochemistry observation information into the plans of the Global Climate Observing System in support of the United Nations Framework Convention on Climate Change, the World Summit on Sustainable Development, the Group on Earth Observations, and other international and intergovernmental strategies. We would like to update our partners across disciplines and domains on our short- and long-term strategies as well as learn from their combined experience and knowledge so that our individual activities align more with those undertaken by our counterparts in biological and physical oceanography as well as in terrestrial and atmospheric domains.

[Roles of soil dissolved organic carbon in carbon cycling of terrestrial ecosystems: a review].

PubMed

Li, Ling; Qiu, Shao-Jun; Liu, Jing-Tao; Liu, Qing; Lu, Zhao-Hua

2012-05-01

Soil dissolved organic carbon (DOC) is an active fraction of soil organic carbon pool, playing an important role in the carbon cycling of terrestrial ecosystems. In view of the importance of the carbon cycling, this paper summarized the roles of soil DOC in the soil carbon sequestration and greenhouse gases emission, and in considering of our present ecological and environmental problems such as soil acidification and climate warming, discussed the effects of soil properties, environmental factors, and human activities on the soil DOC as well as the response mechanisms of the DOC. This review could be helpful to the further understanding of the importance of soil DOC in the carbon cycling of terrestrial ecosystems and the reduction of greenhouse gases emission.

Carbon-Carbon Recuperators in Closed-Brayton-Cycle Nuclear Space Power Systems: A Feasibility Assessment

NASA Technical Reports Server (NTRS)

Barrett, Michael J.; Johnson, Paul K.

2004-01-01

The feasibility of using carbon-carbon recuperators in closed-Brayton-cycle (CBC) nuclear space power conversion systems (PCS) was assessed. Recuperator performance expectations were forecast based on projected thermodynamic cycle state values for a planetary mission. Resulting thermal performance, mass and volume for a plate-fin carbon-carbon recuperator were estimated and quantitatively compared with values for a conventional offset-strip-fin metallic design. Material compatibility issues regarding carbon-carbon surfaces exposed to the working fluid in the CBC PCS were also discussed.

The NASA Carbon Monitoring System

NASA Astrophysics Data System (ADS)

Hurtt, G. C.

2015-12-01

Greenhouse gas emission inventories, forest carbon sequestration programs (e.g., Reducing Emissions from Deforestation and Forest Degradation (REDD and REDD+), cap-and-trade systems, self-reporting programs, and their associated monitoring, reporting and verification (MRV) frameworks depend upon data that are accurate, systematic, practical, and transparent. A sustained, observationally-driven carbon monitoring system using remote sensing data has the potential to significantly improve the relevant carbon cycle information base for the U.S. and world. Initiated in 2010, NASA's Carbon Monitoring System (CMS) project is prototyping and conducting pilot studies to evaluate technological approaches and methodologies to meet carbon monitoring and reporting requirements for multiple users and over multiple scales of interest. NASA's approach emphasizes exploitation of the satellite remote sensing resources, computational capabilities, scientific knowledge, airborne science capabilities, and end-to-end system expertise that are major strengths of the NASA Earth Science program. Through user engagement activities, the NASA CMS project is taking specific actions to be responsive to the needs of stakeholders working to improve carbon MRV frameworks. The first phase of NASA CMS projects focused on developing products for U.S. biomass/carbon stocks and global carbon fluxes, and on scoping studies to identify stakeholders and explore other potential carbon products. The second phase built upon these initial efforts, with a large expansion in prototyping activities across a diversity of systems, scales, and regions, including research focused on prototype MRV systems and utilization of COTS technologies. Priorities for the future include: 1) utilizing future satellite sensors, 2) prototyping with commercial off-the-shelf technology, 3) expanding the range of prototyping activities, 4) rigorous evaluation, uncertainty quantification, and error characterization, 5) stakeholder engagement, 6) partnerships with other U.S. agencies and international partners, and 7) modeling and data assimilation.

40 CFR Table 3 to Subpart Mmm of... - Monitoring Requirements for Control Devices a

Code of Federal Regulations, 2013 CFR

2013-07-01

... regeneration stream mass or volumetric flow during carbon bed regeneration cycle(s) 1. For each regeneration cycle, record the total regeneration stream mass or volumetric flow. Carbon bed temperature monitoring device 2. Temperature of carbon bed after regeneration 2. For each regeneration cycle, record the maximum...

40 CFR Table 3 to Subpart Mmm of... - Monitoring Requirements for Control Devices a

Code of Federal Regulations, 2014 CFR

2014-07-01

... regeneration stream mass or volumetric flow during carbon bed regeneration cycle(s) 1. For each regeneration cycle, record the total regeneration stream mass or volumetric flow. Carbon bed temperature monitoring device 2. Temperature of carbon bed after regeneration 2. For each regeneration cycle, record the maximum...

A Coupled Epipelagic-Meso/Bathypelagic Particle Flux Model for the Bermuda Atlantic Time-series Station (BATS)/Oceanic Flux Program (OFP) Site

NASA Astrophysics Data System (ADS)

Glover, D. M.; Conte, M.

2002-12-01

Of considerable scientific interest is the role remineralization plays in the global carbon cycle. It is the ``biological pump'' that fixes carbon in the upper water column and exports it for long time periods to the deep ocean. From a global carbon cycle point-of-view, it is the processes that govern remineralization in the mid- to deep-ocean waters that provide the feedback to the biogeochemical carbon cycle. In this study we construct an ecosystem model that serves as a mechanistic link between euphotic processes and mesopelagic and bathypelagic processes. We then use this prognostic model to further our understanding of the unparalleled time-series of deep-water sediment traps (21+ years) at the Oceanic Flux Program (OFP) and the euphotic zone measurements (10+ years) at the Bermuda Atlantic Time-series Site (BATS). At the core of this mechanistic ecosystem model of the mesopelagic zone is a model that consists of an active feeding habit zooplankton, a passive feeding habit zooplankton, large detritus (sinks), small detritus (non-sinking), and a nutrient pool. As the detritus, the primary source of food, moves through the water column it is fed upon by the active/passive zooplankton pair and undergoes bacterially mediated remineralization into nutrients. The large detritus pool at depth gains material from the formation of fecal pellets from the passive and active zooplankton. Sloppy feeding habits of the active zooplankton contribute to the small detrital pool. Zooplankton mortality (both classes) also contribute directly to the large detritus pool. Aggregation and disaggregation transform detrital particles from one pool to the other and back again. The nutrients at each depth will gain from detrital remineralization and zooplankton excretion. The equations that model the active zooplankton, passive zooplankton, large detritus, small detritus, and nutrients will be reviewed, results shown and future model modifications discussed.

Geologic Carbon Sequestration and Biosequestration (Carbon Cycle 2.0)

ScienceCinema

DePaolo, Don

2018-05-02

Don DePaolo, Director of LBNL's Earth Sciences Division, speaks at the Carbon Cycle 2.0 kick-off symposium Feb. 3, 2010. We emit more carbon into the atmosphere than natural processes are able to remove - an imbalance with negative consequences. Carbon Cycle 2.0 is a Berkeley Lab initiative to provide the science needed to restore this balance by integrating the Labs diverse research activities and delivering creative solutions toward a carbon-neutral energy future.

Computer program for thermodynamic analysis of open cycle multishaft power system with multiple reheat and intercool

NASA Technical Reports Server (NTRS)

Glassman, A. J.

1974-01-01

A computer program to analyze power systems having any number of shafts up to a maximum of five is presented. On each shaft there can be as many as five compressors and five turbines, along with any specified number of intervening intercoolers and reheaters. A recuperator can be included. Turbine coolant flow can be accounted for. Any fuel consisting entirely of hydrogen and/or carbon can be used. The program is valid for maximum temperatures up to about 2000 K (3600 R). The system description, the analysis method, a detailed explanation of program input and output including an illustrative example, a dictionary of program variables, and the program listing are explained.

Energy Demand in China (Carbon Cycle 2.0)

ScienceCinema

Price, Lynn

2018-02-14

Lynn Price, LBNL scientist, speaks at the Carbon Cycle 2.0 kick-off symposium Feb. 2, 2010. We emit more carbon into the atmosphere than natural processes are able to remove - an imbalance with negative consequences. Carbon Cycle 2.0 is a Berkeley Lab initiative to provide the science needed to restore this balance by integrating the Labs diverse research activities and delivering creative solutions toward a carbon-neutral energy future.

Biofuels Science and Facilities (Carbon Cycle 2.0)

ScienceCinema

Keasling, Jay D.

2018-04-27

Jay D. Keasling speaks at the Carbon Cycle 2.0 kick-off symposium Feb. 2, 2010. We emit more carbon into the atmosphere than natural processes are able to remove - an imbalance with negative consequences. Carbon Cycle 2.0 is a Berkeley Lab initiative to provide the science needed to restore this balance by integrating the Labs diverse research activities and delivering creative solutions toward a carbon-neutral energy future.

Energy Storage: Breakthrough in Battery Technologies (Carbon Cycle 2.0)

ScienceCinema

Balsara, Nitash

2018-02-12

Nitash Balsara speaks at the Carbon Cycle 2.0 kick-off symposium Feb. 2, 2010. We emit more carbon into the atmosphere than natural processes are able to remove - an imbalance with negative consequences. Carbon Cycle 2.0 is a Berkeley Lab initiative to provide the science needed to restore this balance by integrating the Labs diverse research activities and delivering creative solutions toward a carbon-neutral energy future.

Various supercritical carbon dioxide cycle layouts study for molten carbonate fuel cell application

NASA Astrophysics Data System (ADS)

Bae, Seong Jun; Ahn, Yoonhan; Lee, Jekyoung; Lee, Jeong Ik

2014-12-01

Various supercritical carbon dioxide (S-CO2) cycles for a power conversion system of a Molten Carbonate Fuel Cell (MCFC) hybrid system are studied in this paper. Re-Compressing Brayton (RCB) cycle, Simple Recuperated Brayton (SRB) cycle and Simple Recuperated Transcritical (SRT) cycle layouts were selected as candidates for this study. In addition, a novel concept of S-CO2 cycle which combines Brayton cycle and Rankine cycle is proposed and intensively studied with other S-CO2 layouts. A parametric study is performed to optimize the total system to be compact and to achieve wider operating range. Performances of each S-CO2 cycle are compared in terms of the thermal efficiency, net electricity of the MCFC hybrid system and approximate total volumes of each S-CO2 cycle. As a result, performance and total physical size of S-CO2 cycle can be better understood for MCFC S-CO2 hybrid system and especially, newly suggested S-CO2 cycle shows some success.

40 CFR Table 3 to Subpart Ooo of... - Batch Process Vent Monitoring Requirements

Code of Federal Regulations, 2012 CFR

2012-07-01

... specified in § 63.1416(d). a Carbon adsorber a Total regeneration steam flow or nitrogen flow, or pressure (gauge or absolute) during carbon bed regeneration cycle(s), and Record the total regeneration steam flow or nitrogen flow, or pressure for each carbon bed regeneration cycle. Temperature of the carbon bed...

40 CFR Table 3 to Subpart Ooo of... - Batch Process Vent Monitoring Requirements

Code of Federal Regulations, 2010 CFR

2010-07-01

... specified in § 63.1416(d). a Carbon adsorber a Total regeneration steam flow or nitrogen flow, or pressure (gauge or absolute) during carbon bed regeneration cycle(s), and Record the total regeneration steam flow or nitrogen flow, or pressure for each carbon bed regeneration cycle. Temperature of the carbon bed...

40 CFR Table 3 to Subpart Ooo of... - Batch Process Vent Monitoring Requirements

Code of Federal Regulations, 2011 CFR

2011-07-01

... specified in § 63.1416(d). a Carbon adsorber a Total regeneration steam flow or nitrogen flow, or pressure (gauge or absolute) during carbon bed regeneration cycle(s), and Record the total regeneration steam flow or nitrogen flow, or pressure for each carbon bed regeneration cycle. Temperature of the carbon bed...

Finding of No Significant Impact & Tiered Environmental Assessment: Public Law 84-99 Rehabilitation Program Levee Unit 624-627 - Mosquito Creek Pottawattamie County, Iowa

DTIC Science & Technology

2014-10-01

production; materials cycling (e.g., nitrogen, carbon, oxygen, phosphorous, and sulfur ); transformation, detoxification, and sequestration of pollutants and...be removed or covered by other material, such as concrete, asphalt , soil, gravel, etc. Temporary fills may be placed upon the substrate, but must be

Improved low temperature performance of lithium ion cells with low ethylene carbonate content electrolytes

NASA Technical Reports Server (NTRS)

Smart, M.; Ratnakumar, B. V.; Surampudi, S.; Crott, H.; Tice, D.; Staniewicz, R.

2001-01-01

Lithium-ion rechargeable batteries are being developed for various aerospace applications under a NASA-DoD interagency program. For the projected missions, lithium ion batteries need to be further improved, i.e., low temperature performance for Mars Landers, Rovers, and Penetrators and cycle life for the Orbiters and LEO and GEO satellites.

Characterization of cookstove emissions from various stoves, fuels, and cycles; intervention pathways and implications for climate

NASA Astrophysics Data System (ADS)

DeCarlo, P. F.; Jetter, J.; Khan, B.; Zhao, Y.; Yelverton, T.; Hays, M. D.

2011-12-01

Nearly half of the world's population relies on inefficient open fire or rudimentary cookstoves to prepare their food. Combustion of biomass or other fuels results in not only high indoor air pollution, but is also a large source of climate forcing species such as black and organic carbon species to the earth's atmosphere. Large-scale intervention programs are now underway to replace inefficient cooking methods with newer technologies. These intervention programs have as a goal the improvement of indoor air pollution and reduction of negative climate impacts. To characterize the current available alternatives, a major cookstove testing program was conducted at the US EPA. This presentation will focus on the characterization of the emission measurements for a variety of different cookstoves, fuels and cooking cycles. The work will focus on the aerosol optical properties measured with a PASS-3, and the climate impacts of various intervention pathways will be discussed.

Climate extremes and the carbon cycle.

PubMed

Reichstein, Markus; Bahn, Michael; Ciais, Philippe; Frank, Dorothea; Mahecha, Miguel D; Seneviratne, Sonia I; Zscheischler, Jakob; Beer, Christian; Buchmann, Nina; Frank, David C; Papale, Dario; Rammig, Anja; Smith, Pete; Thonicke, Kirsten; van der Velde, Marijn; Vicca, Sara; Walz, Ariane; Wattenbach, Martin

2013-08-15

The terrestrial biosphere is a key component of the global carbon cycle and its carbon balance is strongly influenced by climate. Continuing environmental changes are thought to increase global terrestrial carbon uptake. But evidence is mounting that climate extremes such as droughts or storms can lead to a decrease in regional ecosystem carbon stocks and therefore have the potential to negate an expected increase in terrestrial carbon uptake. Here we explore the mechanisms and impacts of climate extremes on the terrestrial carbon cycle, and propose a pathway to improve our understanding of present and future impacts of climate extremes on the terrestrial carbon budget.

KSC-08pd2046

NASA Image and Video Library

2008-07-14

VANDENBERG AIR FORCE BASE, Calif. -- An Alliant motor designated for Stage 3 of a Taurus rocket is weighed by Orbital Sciences workers in Building 1555 at Vandenberg AFB. The Taurus will launch the Orbiting Carbon Observatory, or OCO, in January 2009. The OCO is a new Earth-orbiting mission sponsored by NASA's Earth System Science Pathfinder Program. OCO will provide space-based observations of atmospheric carbon dioxide (CO2), the principal human-initiated driver of climate change. Mature technologies will be used to address NASA's highest priority carbon cycle measurement requirement. NASA's Jet Propulsion Laboratory leads the OCO effort. Orbital Sciences Corporation is providing the Taurus launch vehicle; Hamilton Sundstrand Sensor Systems, the OCO spacecraft. Photo credit: NASA/Randy Beaudoin

KSC-08pd2044

NASA Image and Video Library

2008-07-14

VANDENBERG AIR FORCE BASE, Calif. -- An Alliant motor designated for Stage 3 of a Taurus rocket is weighed by Orbital Sciences workers in Building 1555 at Vandenberg AFB. The Taurus will launch the Orbiting Carbon Observatory, or OCO, in January 2009. The OCO is a new Earth-orbiting mission sponsored by NASA's Earth System Science Pathfinder Program. OCO will provide space-based observations of atmospheric carbon dioxide (CO2), the principal human-initiated driver of climate change. Mature technologies will be used to address NASA's highest priority carbon cycle measurement requirement. NASA's Jet Propulsion Laboratory leads the OCO effort. Orbital Sciences Corporation is providing the Taurus launch vehicle; Hamilton Sundstrand Sensor Systems, the OCO spacecraft. Photo credit: NASA/Randy Beaudoin

KSC-08pd2045

NASA Image and Video Library

2008-07-14

VANDENBERG AIR FORCE BASE, Calif. -- An Alliant motor designated for Stage 3 of a Taurus rocket is weighed by Orbital Sciences workers in Building 1555 at Vandenberg AFB. The Taurus will launch the Orbiting Carbon Observatory, or OCO, in January 2009. The OCO is a new Earth-orbiting mission sponsored by NASA's Earth System Science Pathfinder Program. OCO will provide space-based observations of atmospheric carbon dioxide (CO2), the principal human-initiated driver of climate change. Mature technologies will be used to address NASA's highest priority carbon cycle measurement requirement. NASA's Jet Propulsion Laboratory leads the OCO effort. Orbital Sciences Corporation is providing the Taurus launch vehicle; Hamilton Sundstrand Sensor Systems, the OCO spacecraft. Photo credit: NASA/Randy Beaudoin

Facilities, testing, and continuing studies on carbon-black loaded styrene-butadiene rubber

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

Goldberg, A.; Sanchez, R.J.; LeMay, J.D.

The Lawrence Livermore National Laboratory (LLNL) has been involved with investigations dealing with the response of the rubber in tank track pads to various loading scenarios, both in the field and in the laboratory. In the laboratory, numerous studies were also performed on a number of other rubber formulations primarily involving a range of carbon-black loadings in SBR and NR. Reference is made to reports and papers addressing each of the studies involved in this program. Work performed during the final stages of this program is described. These studies were directed primarily at developing an understanding of the effects ofmore » cycling and notching histories, notch radius, notch depth, and specimen thickness on the deformation behavior, strain distributions, hysteresis, and residual strength of SBR containing various amounts of carbon black. Significant improvements were realized in our testing methodology, computer-controlled facilities, and data-acquisition system, and in our ability to obtain continuous photomicrographic documentation in ''real time'' of the tearing improvements, as they relate to the various studies, are detailed in this document. Results obtained in these studied involve (1) the fabrication and testing of thick tensile specimens, (2) the effect of notching under load on the residual strength, (3) the effect of cycling on residual strength of notched and notch-free specimens, (4) the effect of cycling on hysteresis, (5) the effect of notch radius for various notch depths on loss of strength, and (6) evaluation of strain at a notch tip and remote from the notch tip at various specimen extensions by analyzing the specimen grid markings, which were obtained with the microscope-video-Polaroid system. 15 refs., 27 figs.« less

Analysis of Co-spatial UV-Optical STIS Spectra of Seven Planetary Nebulae From HST Cycle 19 GO 12600

NASA Astrophysics Data System (ADS)

Miller, Timothy R.; Henry, Richard B. C.; Dufour, Reginald J.; Kwitter, Karen B.; Shaw, Richard A.; Balick, Bruce; Corradi, Romano

2016-01-01

We present an analysis of seven spatially resolved planetary nebulae (PNe), NGC 2440, NGC 3242, NGC 5315, NGC 5882, NGC 7662, IC 2165, and IC 3568, from observations in the Cycle 19 program GO 12600 using HST STIS. These seven observations cover the wavelength range 1150-10,270 Å with 0.2 and 0.5 arcsec wide slits, and are co-spatial to within 0.1 arcsec along a 25 arcsec length across each nebula. The wavelength and spatial coverage enabled a detailed study of physical conditions and abundances from UV and optical line emissions (compared to only optical lines) for these seven PNe. The first UV lines of interest are those of carbon. The resolved lines of C III] 1906.68 and 1908.73 yielded a direct measurement of the density within the volume occupied by doubly-ionized carbon and other similar co-spatial ions as well as contributed to an accurate measurement of the carbon abundance. Each PN spectrum was divided into smaller spatial regions or segments in order to assess inferred density variations among the regions along the entire slit. There is a clear difference in the inferred density for several regions of each PNe. Variations in electron temperature and chemical abundances were also probed and shown to be completely homogeneous within the errors. Lastly, these nebulae were modeled in detail with the photoionization code CLOUDY. This modeling constrained the central star parameters of temperature and luminosity and tested the effects different density profiles have on these parameters. We gratefully acknowledge generous support from NASA through grants related to the Cycle 19 program GO 12600, as well as from the University of Oklahoma.

Nonautonomous linear system of the terrestrial carbon cycle

NASA Astrophysics Data System (ADS)

Luo, Y.

2012-12-01

Carbon cycle has been studied by uses of observation through various networks, field and laboratory experiments, and simulation models. Much less has been done on theoretical thinking and analysis to understand fundament properties of carbon cycle and then guide observatory, experimental, and modeling research. This presentation is to explore what would be the theoretical properties of terrestrial carbon cycle and how those properties can be used to make observatory, experimental, and modeling research more effective. Thousands of published data sets from litter decomposition and soil incubation studies almost all indicate that decay processes of litter and soil organic carbon can be well described by first order differential equations with one or more pools. Carbon pool dynamics in plants and soil after disturbances (e.g., wildfire, clear-cut of forests, and plows of soil for cropping) and during natural recovery or ecosystem restoration also exhibit characteristics of first-order linear systems. Thus, numerous lines of empirical evidence indicate that the terrestrial carbon cycle can be adequately described as a nonautonomous linear system. The linearity reflects the nature of the carbon cycle that carbon, once fixed by photosynthesis, is linearly transferred among pools within an ecosystem. The linear carbon transfer, however, is modified by nonlinear functions of external forcing variables. In addition, photosynthetic carbon influx is also nonlinearly influenced by external variables. This nonautonomous linear system can be mathematically expressed by a first-order linear ordinary matrix equation. We have recently used this theoretical property of terrestrial carbon cycle to develop a semi-analytic solution of spinup. The new methods have been applied to five global land models, including NCAR's CLM and CABLE models and can computationally accelerate spinup by two orders of magnitude. We also use this theoretical property to develop an analytic framework to decompose modeled carbon cycle into a few traceable components so as to facilitate model intercompsirosn, benchmark analysis, and data assimilation of global land models.

Matrix approach to uncertainty assessment and reduction for modeling terrestrial carbon cycle

NASA Astrophysics Data System (ADS)

Luo, Y.; Xia, J.; Ahlström, A.; Zhou, S.; Huang, Y.; Shi, Z.; Wang, Y.; Du, Z.; Lu, X.

2017-12-01

Terrestrial ecosystems absorb approximately 30% of the anthropogenic carbon dioxide emissions. This estimate has been deduced indirectly: combining analyses of atmospheric carbon dioxide concentrations with ocean observations to infer the net terrestrial carbon flux. In contrast, when knowledge about the terrestrial carbon cycle is integrated into different terrestrial carbon models they make widely different predictions. To improve the terrestrial carbon models, we have recently developed a matrix approach to uncertainty assessment and reduction. Specifically, the terrestrial carbon cycle has been commonly represented by a series of carbon balance equations to track carbon influxes into and effluxes out of individual pools in earth system models. This representation matches our understanding of carbon cycle processes well and can be reorganized into one matrix equation without changing any modeled carbon cycle processes and mechanisms. We have developed matrix equations of several global land C cycle models, including CLM3.5, 4.0 and 4.5, CABLE, LPJ-GUESS, and ORCHIDEE. Indeed, the matrix equation is generic and can be applied to other land carbon models. This matrix approach offers a suite of new diagnostic tools, such as the 3-dimensional (3-D) parameter space, traceability analysis, and variance decomposition, for uncertainty analysis. For example, predictions of carbon dynamics with complex land models can be placed in a 3-D parameter space (carbon input, residence time, and storage potential) as a common metric to measure how much model predictions are different. The latter can be traced to its source components by decomposing model predictions to a hierarchy of traceable components. Then, variance decomposition can help attribute the spread in predictions among multiple models to precisely identify sources of uncertainty. The highly uncertain components can be constrained by data as the matrix equation makes data assimilation computationally possible. We will illustrate various applications of this matrix approach to uncertainty assessment and reduction for terrestrial carbon cycle models.

Program of mineralization and cycling in marine systems: Organic geochemistry of particulates and sediments (CaBS): Progress report, November 15, 1987--November 14, 1988

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

Venkatesan, M.I.; Kaplan, I.R.

1988-11-01

The biogeochemical processes and the dynamics involved in the cycling and transport of organic carbon can be elucidated only by determining distributions of specific organic compounds associated with the particles. At UCLA, the quantitative data of the various organic compounds in the sediment cores and trap particulates from various depths of water column are gathered in order to construct a dynamic model of the biogeochemical cycling and processes occurring in the water and sedimentary columns. The sources of organic carbon in southern California Bight derive from both terrestrial and marine regimes. The varied organic carbon sources can be reasonably delineatedmore » within limits by the organic geochemical approach of determining various characteristic biomarkers, as well as a variety of pollution indicators. The distributions of organic biomarker compounds are characteristic of marine algae, terrestrial vascular plants, bacteria, etc. Presence of specific biomarkers also indicate the occurrence of specific species (e.g., dinosterol specific of dinoflagellates). There are some pollution indicators which one can look for in the marine environment to trace their origin to terrestrial inputs, i.e., polycyclic aromatic hydrocarbons from petroleum and combustion, coprostanol from sewage, etc. We study the distribution of many of these compounds and from a correlation of their relative abundance, an attempt is made to delineate marine vs terrestrial influx to the organic carbon in the study area. 18 refs., 1 fig., 4 tabs.« less

Estimates of Fossil Fuel Carbon Dioxide Emissions From Mexico at Monthly Time Intervals

NASA Astrophysics Data System (ADS)

Losey, L. M.; Andres, R. J.

2003-12-01

Human consumption of fossil fuels has greatly contributed to the rise of carbon dioxide in the Earth's atmosphere. To better understand the global carbon cycle, it is important to identify the major sources of these fossil fuels. Mexico is among the top fifteen nations in the world for producing fossil fuel carbon dioxide emissions. Based on this information and that emissions from Mexico are a focus of the North American Carbon Program, Mexico was selected for this study. Mexican monthly inland sales volumes for January 1988-May 2003 were collected on natural gas and liquid fuels from the Energy Information Agency in the United States Department of Energy. These sales figures represent a major portion of the total fossil fuel consumption in Mexico. The fraction of a particular fossil fuel consumed in a given month was determined by dividing the monthly sales volumes by the annual sum of monthly sales volumes for a given year. This fraction was then multiplied by the annual carbon dioxide values reported by the Carbon Dioxide Information Analysis Center (CDIAC) at Oak Ridge National Laboratory (ORNL) to estimate the monthly carbon dioxide emissions from the respective fuels. The advantages of this methodology are: 1) monthly fluxes are consistent with the annual flux as determined by the widely-accepted CDIAC values, and 2) its general application can be easily adapted to other nations for determining their sub-annual time scale emissions. The major disadvantage of this methodology is the proxy nature inherent to it. Only a fraction of the total emissions are used as an estimate in determining the seasonal cycle. The error inherent in this approach increases as the fraction of total emissions represented by the proxy decreases. These data are part of a long-term project between researchers at the University of North Dakota and ORNL which attempts to identify and understand the source(s) of seasonal variations of global, fossil-fuel derived, carbon dioxide emissions. Better knowledge of the temporal variation of the annual fossil fuel flux will lead to a better understanding of the global carbon cycle. This research will be archived at CDIAC for public access.

Carbon Cycle 2.0: Ashok Gadgil: global impact

ScienceCinema

Ashok Gadgi

2017-12-09

Ashok Gadgil speaks at the Carbon Cycle 2.0 kick-off symposium Feb. 2, 2010. We emit more carbon into the atmosphere than natural processes are able to remove - an imbalance with negative consequences. Carbon Cycle 2.0 is a Berkeley Lab initiative to provide the science needed to restore this balance by integrating the Labs diverse research activities and delivering creative solutions toward a carbon-neutral energy future. http://carboncycle2.lbl.gov/

Low Cost Solar Energy Conversion (Carbon Cycle 2.0)

ScienceCinema

Ramesh, Ramamoorthy

2018-04-27

Ramamoorthy Ramesh from LBNL's Materials Science Division speaks at the Carbon Cycle 2.0 kick-off symposium Feb. 2, 2010. We emit more carbon into the atmosphere than natural processes are able to remove - an imbalance with negative consequences. Carbon Cycle 2.0 is a Berkeley Lab initiative to provide the science needed to restore this balance by integrating the Labs diverse research activities and delivering creative solutions toward a carbon-neutral energy future.

Observed and modeled carbon and energy fluxes for agricultural sites under North American Carbon Program site-level interim synthesis

NASA Astrophysics Data System (ADS)

Lokupitiya, E. Y.; Denning, A.

2010-12-01

Croplands are unique, man-made ecosystems with dynamics mostly dependent on human decisions. Crops uptake a significant amount of Carbon dioxide (CO2) during their short growing seasons. Reliability of the available models to predict the carbon exchanges by croplands is important in estimating the cropland contribution towards overall land-atmosphere carbon exchange and global carbon cycle. The energy exchanges from croplands include both sensible and latent heat fluxes. This study focuses on analyzing the performance of 19 land surface models across five agricultural sites under the site-level interim synthesis of North American Carbon Program (NACP). Model simulations were performed using a common simulation protocol and input data, including gap-filled meteorological data corresponding to each site. The net carbon fluxes (i.e. net ecosystem exchange; NEE) and energy fluxes (sensible and latent heat) predicted by 12 models with sub-hourly/hourly temporal resolution and 7 models with daily temporal resolution were compared against the site-specific gap-filled observed flux tower data. Comparisons were made by site and crop type (i.e. maize, soybean, and wheat), mainly focusing on the coefficient of determination, correlation, root mean square error, and standard deviation. Analyses also compared the diurnal, seasonal, and inter-annual variability of the modeled fluxes against the observed data and the mean modeled data.

A Model for the Decrease in Amplitude of Carbon Isotope Excursions Throughout the Phanerozoic

NASA Astrophysics Data System (ADS)

Bachan, A.; Lau, K. V.; Saltzman, M.; Thomas, E.; Kump, L. R.; Payne, J.

2016-12-01

The geological cycling of carbon ties the ocean-­atmosphere carbon pool to Earth's biosphere and sedimentary reservoirs. Perturbations to this coupled system are recorded in the carbon-isotopic (δ13C) composition of marine carbonates. Large amplitude δ13C variations with durations of 0.5 - 10 m.y. are typically treated as individual events and interpreted accordingly. However, a recent compilation of Phanerozoic data reveals a decline in the variance of the δ13C record over time, suggesting a common underlying control. Here we propose that the redox structure of the continental shelves was a key determinant of the sensitivity of the geologic carbon cycle: when oxygen minimum zones (OMZs) were large, shallow, and prone to expansion, recurrent physical forcings (such as sea level and tectonics) would have had the capacity to drive large changes in the areal extent of OMZs, resulting in a strong leverage on δ13C values. Using a simple model of the geologic carbon cycle, we demonstrate that interactions between the carbon and phosphate cycles can result in amplification of recurrent forcings with periods in the 0.5 - 10 m.y. range. Thus, rather than requiring that physical forcings have their largest amplitude of variation on those time scales, enhanced sensitivity of the carbon cycle can account for the characteristic duration of δ13C excursions. Biologically mediated aspects of geologic carbon cycling, including the depth of bioturbation and evolution of pelagic calcifiers, likely drove a decline in the depth and extent of ocean anoxia over the Phanerozoic resulting in the stabilization of the geologic carbon cycle.

The carbon cycle on early Earth--and on Mars?

PubMed

Grady, Monica M; Wright, Ian

2006-10-29

One of the goals of the present Martian exploration is to search for evidence of extinct (or even extant) life. This could be redefined as a search for carbon. The carbon cycle (or, more properly, cycles) on Earth is a complex interaction among three reservoirs: the atmosphere; the hydrosphere; and the lithosphere. Superimposed on this is the biosphere, and its presence influences the fixing and release of carbon in these reservoirs over different time-scales. The overall carbon balance is kept at equilibrium on the surface by a combination of tectonic processes (which bury carbon), volcanism (which releases it) and biology (which mediates it). In contrast to Earth, Mars presently has no active tectonic system; neither does it possess a significant biosphere. However, these observations might not necessarily have held in the past. By looking at how Earth's carbon cycles have changed with time, as both the Earth's tectonic structure and a more sophisticated biology have evolved, and also by constructing a carbon cycle for Mars based on the carbon chemistry of Martian meteorites, we investigate whether or not there is evidence for a Martian biosphere.

The carbon cycle on early Earth—and on Mars?

PubMed Central

Grady, Monica M; Wright, Ian

2006-01-01

One of the goals of the present Martian exploration is to search for evidence of extinct (or even extant) life. This could be redefined as a search for carbon. The carbon cycle (or, more properly, cycles) on Earth is a complex interaction among three reservoirs: the atmosphere; the hydrosphere; and the lithosphere. Superimposed on this is the biosphere, and its presence influences the fixing and release of carbon in these reservoirs over different time-scales. The overall carbon balance is kept at equilibrium on the surface by a combination of tectonic processes (which bury carbon), volcanism (which releases it) and biology (which mediates it). In contrast to Earth, Mars presently has no active tectonic system; neither does it possess a significant biosphere. However, these observations might not necessarily have held in the past. By looking at how Earth's carbon cycles have changed with time, as both the Earth's tectonic structure and a more sophisticated biology have evolved, and also by constructing a carbon cycle for Mars based on the carbon chemistry of Martian meteorites, we investigate whether or not there is evidence for a Martian biosphere. PMID:17008211

Analysis of 12 AH aerospace nickel-cadmium cells from the design variable program

NASA Technical Reports Server (NTRS)

Vasanth, Kunigahalli L.; Morrow, George

1987-01-01

The Design Variable Program of NASA/GSFC provided a systematic approach to evaluate the performance of 12 Ampere-Hour Nickel-Cadmium cells of different designs. Design Variables tested in this program included teflonated negative plates, silver treated negative plates, lightly loaded negative plates, positive plates with no cadmium treatment, plate design of 1968 utilizing old and new processing techniques and electrochemically impregnated positive plates. These cells were life cycled in a Low-Earth Orbit (LEO) regime for 3 to 4 years. Representative cells taken from the Design Variable Program were examined via chemical, electrochemical and surface analyses. The results indicate the following: (1) positive swelling and carbonate content in the electrolyte increase as a function of number of cycles; (2) electrolyte distribution follows a general order NEG greater than POS greater than SEP; (3) control and No PQ groups outperformed the rest of the groups; and (4) the polyproylene group exhibited heavy cadmium migration and poor performance.

Estimation of soil organic carbon in forests of the United States

NASA Astrophysics Data System (ADS)

Domke, G. M.; Perry, C. H.; Walters, B. F.; Woodall, C. W.; Nave, L. E.; Swanston, C.

2015-12-01

Soil organic carbon (SOC) is the largest terrestrial carbon (C) sink on earth and management of this pool is a critical component of global efforts to mitigate atmospheric C concentrations. Soil organic carbon is also a key indicator of soil quality as it affects essential biological, chemical, and physical soil functions such as nutrient cycling, water retention, and soil structure maintenance. Much of the SOC on earth is found in forest ecosystems and is thought to be relatively stable. That said, there is growing evidence that SOC may be sensitive to disturbance and global change drivers. In the United States (US), SOC in forests is monitored by the national forest inventory (NFI) conducted by the Forest Inventory and Analysis (FIA) program within the US Department of Agriculture, Forest Service. The FIA program currently uses SOC predictions based on SSURGO/STATSGO data to populate the NFI. Most of estimates of SOC in forests from the SSURGO/STATSGO data are based primarily upon expert opinion and lack systematic field observations. The FIA program has been consistently measuring soil attributes as part of the NFI since 2001 and has amassed an extensive inventory of SOC in forests in the conterminous US and coastal Alaska. Here we present estimates of SOC obtained using data from the NFI and International Soil Carbon Network and describe the modeling framework used to compile estimates for United Nations Framework Convention on Climate Change reporting.

CarboNA: International Studies of the North American Carbon Cycle

NASA Astrophysics Data System (ADS)

Denning, S.; Cavallaro, N.; Ste-Marie, C.; Muhlia-Melo, A.

2009-05-01

A Science Steering Committee has been formed consisting of carbon cycle scientists from Canada, Mexico, and the United States and government agency contacts from each country, to draft a Science Plan for CarboNA. Science questions that we will address include: 1. What's the current carbon budget of NA and adjacent oceans, including spatial structure and seasonal-to- interannual variations? 2. What mechanisms are involved? What processes control the time mean vs the interannual variability? 3. When will sinks saturate? Will they become sources? Are there surprises in store? What roles will be played by melting permafrost, boreal warming, and subtropical desertification, and tropical development? 4. What are the likely responses of terrestrial ecosystems and coastal oceans to climate change and enhanced CO2? 5. What roles will economic development, energy technology, and trade play in mitigating increases in fossil fuel emissions? In addition to the national research programs already underway in the three countries, we anticipate special collaborative projects of international scope. For example: 1. Studies of the response of terrestrial ecosystems to climate change along an ecological gradient from the Arctic to the Tropics; 2. Truly continental budgets for atmospheric greenhouse gases using data from land-based, airborne, marine, and spaceborne platforms; 3. An aggressively interdisciplinary intensive experiment to understand and quantify carbon cycle processes and budgets in the Gulf of Mexico Basin; 4. Investigation of the turrent state and likely future changes in carbon cycling in coastal ocean environments, including river inputs of POC, DOC, DIC, and nutrients; impacts on fisheries and coastal economies; exchange between coastal oceans and deep ocean basins; and air-sea gas exchange; 5. Government-level agreements on data sharing and harmonization, including but not limited to forest inventories, agricultural data, fossil fuel emissions data, land-use data, energy and population and vehicle miles traveled, flux towers, trace gas measurements, etc. CarboNA will be introduced, and the process and content of current discussions will be presented.

The future of the North American carbon cycle - projections and associated climate change

NASA Astrophysics Data System (ADS)

Huntzinger, D. N.; Chatterjee, A.; Cooley, S. R.; Dunne, J. P.; Hoffman, F. M.; Luo, Y.; Moore, D. J.; Ohrel, S. B.; Poulter, B.; Ricciuto, D. M.; Tzortziou, M.; Walker, A. P.; Mayes, M. A.

2016-12-01

Approximately half of anthropogenic emissions from the burning of fossil fuels is taken up annually by carbon sinks on the land and in the oceans. However, there are key uncertainties in how carbon uptake by terrestrial, ocean, and freshwater systems will respond to, and interact with, climate into the future. Here, we outline the current state of understanding on the future carbon budget of these major reservoirs within North America and the globe. We examine the drivers of future carbon cycle changes, including carbon-climate feedbacks, atmospheric composition, nutrient availability, and human activity and management decisions. Progress has been made at identifying vulnerabilities in carbon pools, including high-latitude permafrost, peatlands, freshwater and coastal wetlands, and ecosystems subject to disturbance events, such as insects, fire and drought. However, many of these processes/pools are not well represented in current models, and model intercomparison studies have shown a range in carbon cycle response to factors such as climate and CO2 fertilization. Furthermore, as model complexity increases, understanding the drivers of model spread becomes increasingly more difficult. As a result, uncertainties in future carbon cycle projections are large. It is also uncertain how management decisions and policies will impact future carbon stocks and flows. In order to guide policy, a better understanding of the risk and magnitude of North American carbon cycle changes is needed. This requires that future carbon cycle projections be conditioned on current observations and be reported with sufficient confidence and fully specified uncertainties.

The changing global carbon cycle: linking local plant-soil carbon dynamics to global consequences

Treesearch

F. Stuart Chapin; Jack McFarland; A. David McGuire; Eugenie S. Euskirchen; Roger W. Ruess; Knut Kielland

2009-01-01

Most current climate-carbon cycle models that include the terrestrial carbon (C) cycle are based on a model developed 40 years ago by Woodwell & Whittaker (1968) and omit advances in biogeochemical understanding since that time. Their model treats net C emissions from ecosystems as the balance between net primary production (NPP) and heterotrophic respiration (HR,...

Ultra-long-term cycling stability of an integrated carbon-sulfur membrane with dual shuttle-inhibiting layers of graphene "nets" and a porous carbon skin.

PubMed

Liu, Mingkai; Meng, Qinghua; Yang, Zhiyuan; Zhao, Xinsheng; Liu, Tianxi

2018-05-15

An integrated carbon-sulfur (CSG/PC) membrane with dual shuttle-inhibiting layers was prepared by inserting graphene "nets" and a porous carbon (PC) skin, and the membrane achieved an extraordinary cycling stability up to 1000 cycles with an average Coulombic efficiency of ∼100%.

The Atmospheric Constraint: What we Know About the State of the Carbon Cycle by Observing Carbon Dioxide and Methane

NASA Astrophysics Data System (ADS)

Denning, S.; Jacobson, A. R.; Miller, J. B.; Ballantyne, A.; Bruhwiler, L.; Chatterjee, A.; Davis, K. J.; Duncan, B. N.; Gurney, K. R.; Houghton, R. A.; Keppel-Aleks, G.; Michalak, A. M.; Ott, L.

2016-12-01

Much of what is known about the global carbon cycle has been learned by studying the time rate of change and spatial distribution of carbon gases in the atmosphere. In the past decade, the network of measurements of atmospheric CO2 and CH4 has increased by leaps and bounds. Observations now include many programs of sample collection; commercial as well as academic and government measurement programs; in-situ measurements from towers, ships, and aircraft; and new satellite sensors with near-global coverage. Quantitative estimates of regional budgets for both CO2 and CH4 require atmospheric tracer transport inversion. These methods have been further developed and improved in recent years and several groups are now providing updated regional fluxes using a suite of such models. Analysis of atmospheric CO2 has shown that ongoing sink processes continue to sequester about half of global fossil fuel emissions, with about half the sink activity on land and half in the oceans. Enhanced observing and improved inverse modeling of CO2 has been evaluated for smaller regions and shown to match direct carbon inventories. Aircraft sampling and satellite observations have finally begun to converge on the partition between tropical and extratropical land sinks and on the influence of climate variability. Additional tracers such as 13CO2, 14CO2, and COS as well as new remote sensing products such as solar induced fluorescence are helping carbon cycle scientists to better understand and predict sink mechanisms. An emerging area of work is the use of atmospheric data to conduct monitoring, reporting, and verification of emissions from point sources and cities. A major field campaign to study CO2 transport by convective and frontal storms is now underway. After a period of stable concentrations, concentrations of atmospheric CH4 have again begun to increase. Campaigns using mobile instruments and in-situ measurements made from fixed towers have established that leakage of CH4 associated with oil and gas extraction is greater than had previously been estimated. A dedicated field campaigns to study CH4 sources in the Arctic have carefully quantified emissions from seasonal sources such as wetlands and forests as well as point sources.

Cyclic process for producing methane from carbon monoxide with heat removal

DOEpatents

Frost, Albert C.; Yang, Chang-lee

1982-01-01

Carbon monoxide-containing gas streams are converted to methane by a cyclic, essentially two-step process in which said carbon monoxide is disproportionated to form carbon dioxide and active surface carbon deposited on the surface of a catalyst, and said carbon is reacted with steam to form product methane and by-product carbon dioxide. The exothermic heat of reaction generated in each step is effectively removed during each complete cycle so as to avoid a build up of heat from cycle-to-cycle, with particularly advantageous techniques being employed for fixed bed, tubular and fluidized bed reactor operations.

Carbon Cycle 2.0: Paul Alivisatos: Introduction

ScienceCinema

Paul Alivisatos

2017-12-09

Berkeley Lab Director Paul Alivisatos speaks at the Carbon Cycle 2.0 kick-off symposium Feb. 1, 2010. Humanity emits more carbon into the atmosphere than natural processes are able to remove - an imbalance with negative consequences.Carbon Cycle 2.0 is a Berkeley Lab initiative to provide the science needed to restore this balance by integrating the Labs diverse research activities and delivering creative solutions toward a carbon-neutral energy future. http://carboncycle2.lbl.gov/

Carbon Cycle 2.0: Mary Ann Piette: Impact of efficient buildings

ScienceCinema

Mary Ann Piette

2017-12-09

Mary Ann Piette speaks at the Carbon Cycle 2.0 kick-off symposium Feb. 2, 2010. We emit more carbon into the atmosphere than natural processes are able to remove - an imbalance with negative consequences. Carbon Cycle 2.0 is a Berkeley Lab initiative to provide the science needed to restore this balance by integrating the Labs diverse research activities and delivering creative solutions toward a carbon-neutral energy future. http://carboncycle2.lbl.gov/

Carbon Cycle 2.0: Bill Collins: A future without CC2.0

ScienceCinema

Bill Collins

2017-12-09

Bill Collins speaks at the Carbon Cycle 2.0 kick-off symposium Feb. 1, 2010. We emit more carbon into the atmosphere than natural processes are able to remove - an imbalance with negative consequences. Carbon Cycle 2.0 is a Berkeley Lab initiative to provide the science needed to restore this balance by integrating the Labs diverse research activities and delivering creative solutions toward a carbon-neutral energy future. http://carboncycle2.lbl.gov/

Carbon Cycle 2.0: Mary Ann Piette: Impact of efficient buildings

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

Mary Ann Piette

Mary Ann Piette speaks at the Carbon Cycle 2.0 kick-off symposium Feb. 2, 2010. We emit more carbon into the atmosphere than natural processes are able to remove - an imbalance with negative consequences. Carbon Cycle 2.0 is a Berkeley Lab initiative to provide the science needed to restore this balance by integrating the Labs diverse research activities and delivering creative solutions toward a carbon-neutral energy future. http://carboncycle2.lbl.gov/

Carbon Cycle 2.0: Bill Collins: A future without CC2.0

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

Bill Collins

2010-02-09

Bill Collins speaks at the Carbon Cycle 2.0 kick-off symposium Feb. 1, 2010. We emit more carbon into the atmosphere than natural processes are able to remove - an imbalance with negative consequences. Carbon Cycle 2.0 is a Berkeley Lab initiative to provide the science needed to restore this balance by integrating the Labs diverse research activities and delivering creative solutions toward a carbon-neutral energy future. http://carboncycle2.lbl.gov/

Carbon Cycle 2.0: Paul Alivisatos: Introduction

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

Paul Alivisatos

2010-02-09

Berkeley Lab Director Paul Alivisatos speaks at the Carbon Cycle 2.0 kick-off symposium Feb. 1, 2010. Humanity emits more carbon into the atmosphere than natural processes are able to remove - an imbalance with negative consequences.Carbon Cycle 2.0 is a Berkeley Lab initiative to provide the science needed to restore this balance by integrating the Labs diverse research activities and delivering creative solutions toward a carbon-neutral energy future. http://carboncycle2.lbl.gov/

High-cycle electromechanical aging of dielectric elastomer actuators with carbon-based electrodes

NASA Astrophysics Data System (ADS)

de Saint-Aubin, C. A.; Rosset, S.; Schlatter, S.; Shea, H.

2018-07-01

We present high-cycle aging tests of dielectric elastomer actuators (DEAs) based on silicone elastomers, reporting on the time-evolution of actuation strain and of electrode resistance over millions of cycles. We compare several types of carbon-based electrodes, and for the first time show how the choice of electrode has a dramatic influence on DEA aging. An expanding circle DEA configuration is used, consisting of a commercial silicone membrane with the following electrodes: commercial carbon grease applied manually, solvent-diluted carbon grease applied by stamping (pad printing), loose carbon black powder applied manually, carbon black powder suspension applied by inkjet-printing, and conductive silicone-carbon composite applied by stamping. The silicone-based DEAs with manually applied carbon grease electrodes show the shortest lifetime of less than 105 cycles at 5% strain, while the inkjet-printed carbon powder and the stamped silicone-carbon composite make for the most reliable devices, with lifetimes greater than 107 cycles at 5% strain. These results are valid for the specific dielectric and electrode configurations that were tested: using other dielectrics or electrode formulations would lead to different lifetimes and failure modes. We find that aging (as seen in the change in resistance and in actuation strain versus cycle number) is independent of the actuation frequency from 10 Hz to 200 Hz, and depends on the total accumulated time the DEA spends in an actuated state.

Carbon Cycle Dynamics through the Early Eocene Climatic Optimum: Orbital Couplings to Lacustrine Cycling

NASA Astrophysics Data System (ADS)

Rosengard, S. Z.; Grogan, D. S.; Whiteside, J. H.; van Keuren, M.; Musher, D.

2010-12-01

The early Eocene represents the most recent hothouse climate state of Earth history, a period during which Earth’s surface temperatures warmed and reached a steady peak at the Early Eocene Climatic Optimum (EECO), 53.5-50 Ma. Interspersed through the primary warming interval were several hyperthermals, or rapid peaks in surface temperature and pulses of carbon dioxide into the atmosphere, followed by rapid declines, lasting 10^4 to 10^5 years. Various hypotheses have been offered to explain the climatic triggers during the hothouse interval, including changes in ocean circulation, methane release from hydrates, volcanism, and turnover of terrestrial organic matter, implicating various couplings and feedbacks in the global carbon cycle. The present study investigates the prevailing changes in carbon cycle dynamics that occurred during a specific subinterval of the Early Eocene Climatic Optimum. We sampled a carbon-rich 300-ft ( 1100 kyr) section of lacustrine Green River Formation sediments from the TOSCO core in the Uinta Basin at a one-foot resolution for organic carbon content and δ^{13}C. The compiled data comprise a high-resolution profile of total organic carbon and isotopic organic carbon composition through the section, showing cyclic patterns that we hypothesize reflect orbital signals. Bulk isotopic carbon and shale oil measurements from an earlier Fischer Assay across TOSCO’s entire 1030-ft core were then filtered using the expected frequency of a 23-kyr precession cycle. The overlaid cycles reveal δ^{13}C and oil content to be anti-phase through the 300-ft section, except for an interval of 50 feet (180 kyr) from the Mahogany Zone to the B-groove of the core, where the two measurements are in-phase. Given that shale oil, a proxy for lake primary productivity and carbon burial, and δ^{13}C typically correlate inversely, this short, 180-kyr interval of in-phase variation suggests a significant alteration in the local carbon cycle. These preliminary findings reveal a dynamic, inconstant coupling between precessional variations in solar insolation and the carbon cycle during the EECO. As the organic carbon profile fundamentally records ecosystem processes, this precession-carbon cycle coupling is likely modulated by ecological dynamics within the paleolake, such as changing trophic and community structure. Because precession-driven changes in solar insolation dominantly control hydrology and lake water balance, the lacustrine ecosystem response to such perturbations may have precipitated key shifts in the dynamics of carbon cycling through the most stable interval of Earth’s latest hothouse.

Carbon Cycling and Biosequestration Integrating Biology and Climate Through Systems Science Report from the March 2008 Workshop

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

Graber, J.; Amthor, J.; Dahlman, R.

2008-12-01

One of the most daunting challenges facing science in the 21st Century is to predict how Earth's ecosystems will respond to global climate change. The global carbon cycle plays a central role in regulating atmospheric carbon dioxide (CO{sub 2}) levels and thus Earth's climate, but our basic understanding of the myriad of tightly interlinked biological processes that drive the global carbon cycle remains limited at best. Whether terrestrial and ocean ecosystems will capture, store, or release carbon is highly dependent on how changing climate conditions affect processes performed by the organisms that form Earth's biosphere. Advancing our knowledge of biologicalmore » components of the global carbon cycle is thus crucial to predicting potential climate change impacts, assessing the viability of climate change adaptation and mitigation strategies, and informing relevant policy decisions. Global carbon cycling is dominated by the paired biological processes of photosynthesis and respiration. Photosynthetic plants and microbes of Earth's land-masses and oceans use solar energy to transform atmospheric CO{sub 2} into organic carbon. The majority of this organic carbon is rapidly consumed by plants or microbial decomposers for respiration and returned to the atmosphere as CO{sub 2}. Coupling between the two processes results in a near equilibrium between photosynthesis and respiration at the global scale, but some fraction of organic carbon also remains in stabilized forms such as biomass, soil, and deep ocean sediments. This process, known as carbon biosequestration, temporarily removes carbon from active cycling and has thus far absorbed a substantial fraction of anthropogenic carbon emissions.« less

Ocean Carbon and Biogeochemistry Scoping Workshop on Terrestrial and Coastal Carbon Fluxes in the Gulf of Mexico, St. Petersburg, FL, May 6-8, 2008

USGS Publications Warehouse

Robbins, L.L.; Coble, P.G.; Clayton, T.D.; Cai, W.J.

2009-01-01

Despite their relatively small surface area, ocean margins may have a significant impact on global biogeochemical cycles and, potentially, the global air-sea fluxes of carbon dioxide. Margins are characterized by intense geochemical and biological processing of carbon and other elements and exchange large amounts of matter and energy with the open ocean. The area-specific rates of productivity, biogeochemical cycling, and organic/inorganic matter sequestration are high in coastal margins, with as much as half of the global integrated new production occurring over the continental shelves and slopes (Walsh, 1991; Doney and Hood, 2002; Jahnke, in press). However, the current lack of knowledge and understanding of biogeochemical processes occurring at the ocean margins has left them largely ignored in most of the previous global assessments of the oceanic carbon cycle (Doney and Hood, 2002). A major source of North American and global uncertainty is the Gulf of Mexico, a large semi-enclosed subtropical basin bordered by the United States, Mexico, and Cuba. Like many of the marginal oceans worldwide, the Gulf of Mexico remains largely unsampled and poorly characterized in terms of its air-sea exchange of carbon dioxide and other carbon fluxes. In May 2008, the Ocean Carbon and Biogeochemistry Scoping Workshop on Terrestrial and Coastal Carbon Fluxes in the Gulf of Mexico was held in St. Petersburg, FL, to address the information gaps of carbon fluxes associated with the Gulf of Mexico and to offer recommendations to guide future research. The meeting was attended by over 90 participants from over 50 U.S. and Mexican institutions and agencies. The Ocean Carbon and Biogeochemistry program (OCB; http://www.us-ocb.org/) sponsored this workshop with support from the National Science Foundation, the National Oceanic and Atmospheric Administration, the National Aeronautics and Space Administration, the U.S. Geological Survey, and the University of South Florida. The goal of the workshop was to bring together researchers from multiple disciplines studying terrestrial, aquatic, and marine ecosystems to discuss the state of knowledge in carbon fluxes in the Gulf of Mexico, data gaps, and overarching questions in the Gulf of Mexico system. The discussions at the workshop were intended to stimulate integrated studies of marine and terrestrial biogeochemical cycles and associated ecosystems that will help to establish the role of the Gulf of Mexico in the carbon cycle and how it might evolve in the face of environmental change. The information derived from the plenary sessions, questions, and recommendations formulated by the participants will drive future research projects. Further discussion of carbon dynamics is needed to address scales of variability, the infrastructure required for study, and the modeling framework for cross-system integration. During the workshop, participants discussed and provided a number of priorities and recommendations, which are listed on p. 2 of the report. Participants recognized that the key to understanding the Gulf of Mexico system requires international collaboration with scientists from countries adjacent to the Gulf of Mexico. Improved collaboration across existing research community boundaries will be critical and should be encouraged by the funding agencies.

Student Development of Model-Based Reasoning about Carbon Cycling and Climate Change in a Socio-Scientific Issues Unit

ERIC Educational Resources Information Center

Zangori, Laura; Peel, Amanda; Kinslow, Andrew; Friedrichsen, Patricia; Sadler, Troy D.

2017-01-01

Carbon cycling is a key natural system that requires robust science literacy to understand how and why climate change is occurring. Studies show that students tend to compartmentalize carbon movement within plants and animals and are challenged to make sense of how carbon cycles on a global scale. Studies also show that students hold faulty models…

How Sensitive Is the Carbon Budget Approach to Potential Carbon Cycle Changes?

NASA Astrophysics Data System (ADS)

Matthews, D.

2014-12-01

The recent development of global Earth-system models, which include dynamic representations of both physical climate and carbon cycle processes, has led to new insights about how the climate responds to human carbon dioxide emissions. Notably, several model analyses have now shown that global temperature responds linearly to cumulative CO2 emissions across a wide range of emissions scenarios. This implies that the timing of CO2 emissions does not affect the overall climate response, and allows a finite global carbon carbon budget to be defined for a given global temperature target. This linear climate response, however, emerges from the interaction of several non-linear processes and feedbacks involving how carbon sinks respond to changes in atmospheric CO2 and climate. In this presentation, I will give an overview of how carbon sinks and carbon cycle feedbacks contribute to the overall linearity of the climate response to cumulative emissions, and will assess how robust this relationship is to a range of possible changes in the carbon cycle, including (a) potential positive carbon cycle feedbacks that are not well represented in the current generation of Earth-system models and (b) negative emission scenarios resulting from possible technological strategies to remove CO2 from the atmosphere.

Carbon capture by sorption-enhanced water-gas shift reaction process using hydrotalcite-based material

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

van Selow, E.R.; Cobden, P.D.; Verbraeken, P.A.

2009-05-15

A novel route for precombustion decarbonization is the sorption-enhanced water-gas shift (SEWGS) process. In this process carbon dioxide is removed from a synthesis gas at elevated temperature by adsorption. Simultaneously, carbon monoxide is converted to carbon dioxide by the water-gas shift reaction. The periodic adsorption and desorption of carbon dioxide is induced by a pressure swing cycle, and the cyclic capacity can be amplified by purging with steam. From previous studies is it known that for SEWGS applications, hydrotalcite-based materials are particularly attractive as sorbent, and commercial high-temperature shift catalysts can be used for the conversion of carbon monoxide. Tabletsmore » of a potassium promoted hydrotalcite-based material are characterized in both breakthrough and cyclic experiments in a 2 m tall fixed-bed reactor. When exposed to a mixture of carbon dioxide, steam, and nitrogen at 400{sup o}C, the material shows a breakthrough capacity of 1.4 mmol/g. In subsequent experiments the material was mixed with tablets of promoted iron-chromium shift catalyst and exposed to a mixture of carbon dioxide, carbon monoxide, steam, hydrogen, and nitrogen. It is demonstrated that carbon monoxide conversion can be enhanced to 100% in the presence of a carbon dioxide sorbent. At breakthrough, carbon monoxide and carbon dioxide simultaneously appear at the end of the bed. During more than 300 cycles of adsorption/reaction and desorption, the capture rate, and carbon monoxide conversion are confirmed to be stable. Two different cycle types are investigated: one cycle with a CO{sub 2} rinse step and one cycle with a steam rinse step. The performance of both SEWGS cycles are discussed.« less

40 CFR Table 6 to Subpart Uuuu of... - Continuous Compliance With Operating Limits

Code of Federal Regulations, 2010 CFR

2010-07-01

.... 7. carbon absorber maintain the regeneration frequency, total regeneration stream mass or volumetric flow during carbon bed regeneration and temperature of the carbon bed after regeneration (and within 15 minutes of completing any cooling cycle(s)) for each regeneration cycle within the values established...

40 CFR Table 4 to Subpart Ooo of... - Operating Parameter Levels

Code of Federal Regulations, 2011 CFR

2011-07-01

... specific gravity Condenser Exit temperature Maximum temperature Carbon absorber Total regeneration steam or nitrogen flow, or pressure (gauge or absolute) a during carbon bed regeneration cycle; and temperature of the carbon bed after regeneration (and within 15 minutes of completing any cooling cycle(s)) Maximum...

40 CFR Table 4 to Subpart Ooo of... - Operating Parameter Levels

Code of Federal Regulations, 2013 CFR

2013-07-01

... specific gravity Condenser Exit temperature Maximum temperature Carbon absorber Total regeneration steam or nitrogen flow, or pressure (gauge or absolute) a during carbon bed regeneration cycle; and temperature of the carbon bed after regeneration (and within 15 minutes of completing any cooling cycle(s)) Maximum...

40 CFR Table 6 to Subpart Uuuu of... - Continuous Compliance With Operating Limits

Code of Federal Regulations, 2013 CFR

2013-07-01

.... 7. carbon absorber maintain the regeneration frequency, total regeneration stream mass or volumetric flow during carbon bed regeneration and temperature of the carbon bed after regeneration (and within 15 minutes of completing any cooling cycle(s)) for each regeneration cycle within the values established...

40 CFR Table 4 to Subpart Ooo of... - Operating Parameter Levels

Code of Federal Regulations, 2014 CFR

2014-07-01

... specific gravity Condenser Exit temperature Maximum temperature Carbon absorber Total regeneration steam or nitrogen flow, or pressure (gauge or absolute) a during carbon bed regeneration cycle; and temperature of the carbon bed after regeneration (and within 15 minutes of completing any cooling cycle(s)) Maximum...

40 CFR Table 6 to Subpart Uuuu of... - Continuous Compliance With Operating Limits

Code of Federal Regulations, 2011 CFR

2011-07-01

.... 7. carbon absorber maintain the regeneration frequency, total regeneration stream mass or volumetric flow during carbon bed regeneration and temperature of the carbon bed after regeneration (and within 15 minutes of completing any cooling cycle(s)) for each regeneration cycle within the values established...

40 CFR Table 6 to Subpart Uuuu of... - Continuous Compliance With Operating Limits

Code of Federal Regulations, 2014 CFR

2014-07-01

.... 7. carbon absorber maintain the regeneration frequency, total regeneration stream mass or volumetric flow during carbon bed regeneration and temperature of the carbon bed after regeneration (and within 15 minutes of completing any cooling cycle(s)) for each regeneration cycle within the values established...

40 CFR Table 4 to Subpart Ooo of... - Operating Parameter Levels

Code of Federal Regulations, 2012 CFR

2012-07-01

... temperature Maximum temperature Carbon absorber Total regeneration steam or nitrogen flow, or pressure (gauge or absolute) a during carbon bed regeneration cycle; and temperature of the carbon bed after regeneration (and within 15 minutes of completing any cooling cycle(s)) Maximum flow or pressure; and maximum...

40 CFR Table 6 to Subpart Uuuu of... - Continuous Compliance With Operating Limits

Code of Federal Regulations, 2012 CFR

2012-07-01

.... 7. carbon absorber maintain the regeneration frequency, total regeneration stream mass or volumetric flow during carbon bed regeneration and temperature of the carbon bed after regeneration (and within 15 minutes of completing any cooling cycle(s)) for each regeneration cycle within the values established...

The carbon cycle revisited

NASA Technical Reports Server (NTRS)

Bolin, Bert; Fung, Inez

1992-01-01

Discussions during the Global Change Institute indicated a need to present, in some detail and as accurately as possible, our present knowledge about the carbon cycle, the uncertainties in this knowledge, and the reasons for these uncertainties. We discuss basic issues of internal consistency within the carbon cycle, and end by summarizing the key unknowns.

The effects of climate sensitivity and carbon cycle interactions on mitigation policy stringency

EPA Science Inventory

Climate sensitivity and climate-carbon cycle feedbacks interact to determine how global carbon and energy cycles will change in the future. While the science of these connections is well documented, their economic implications are not well understood. Here we examine the effect o...

Three-Dimensional Water and Carbon Cycle Modeling at High Spatial-Temporal Resolutions

NASA Astrophysics Data System (ADS)

Liao, C.; Zhuang, Q.

2017-12-01

Terrestrial ecosystems in cryosphere are very sensitive to the global climate change due to the presence of snow covers, mountain glaciers and permafrost, especially when the increase in near surface air temperature is almost twice as large as the global average. However, few studies have investigated the water and carbon cycle dynamics using process-based hydrological and biogeochemistry modeling approach. In this study, we used three-dimensional modeling approach at high spatial-temporal resolutions to investigate the water and carbon cycle dynamics for the Tanana Flats Basin in interior Alaska with emphases on dissolved organic carbon (DOC) dynamics. The results have shown that: (1) lateral flow plays an important role in water and carbon cycle, especially in dissolved organic carbon (DOC) dynamics. (2) approximately 2.0 × 104 kg C yr-1 DOC is exported to the hydrological networks and it compromises 1% and 0.01% of total annual gross primary production (GPP) and total organic carbon stored in soil, respectively. This study has established an operational and flexible framework to investigate and predict the water and carbon cycle dynamics under the changing climate.

Global Impacts (Carbon Cycle 2.0)

ScienceCinema

Gadgil, Ashok

2018-05-04

Ashok Gadgil, Faculty Senior Scientist and Acting Director, EETD, also Professor of Environmental Engineering, UC Berkeley, speaks at the Carbon Cycle 2.0 kick-off symposium Feb. 2, 2010. We emit more carbon into the atmosphere than natural processes are able to remove - an imbalance with negative consequences. Carbon Cycle 2.0 is a Berkeley Lab initiative to provide the science needed to restore this balance by integrating the Labs diverse research activities and delivering creative solutions toward a carbon-neutral energy future.

A Comparison of Recent Organic and Inorganic Carbon Isotope Records: Why Do They Covary in Some Settings and Not In Others?

NASA Astrophysics Data System (ADS)

Oehlert, A. M.; Swart, P. K.

2013-12-01

Covariance between inorganic and organic δ13C records has been used to determine whether a deposit has been altered by diagenesis, how the dynamics of the global carbon cycle changed during the production of the sediments in the deposit, and also for chronostratigraphic correlations. Although covariant records are observed in the ancient geologic record in a variety of depositional environments, such comparisons are not widely applied to modern deposits where definitive data regarding sediment producers, sea level fluctuations, and changes in the global carbon cycle are available. This study uses paired δ13C records from cores collected by the Ocean Drilling Program from three modern periplatform settings (the Great Bahama Bank, the Great Australian Bight, and the Great Barrier Reef), and two pelagic settings (the Walvis Ridge, and the Madingley Rise). These sites were selected in order to assess the influence of several different environmental factors including; sediment and organic matter producers, sediment mineralogy, margin architecture, sea level oscillations, and sediment transport pathways. In the three periplatform settings, multiple cores arranged in a margin to basin transect were analyzed in order to provide insights into the effects of downslope sediment transport. The preliminary results of this study suggest that sea level oscillations and margin architecture may artificially generate a covarying relationship in periplatform sediments that is unrelated to changes in the global carbon cycle. Furthermore, preliminary results from the Walvis Ridge and the Madingley Rise sediments suggest that the relationship between inorganic and organic δ13C records may not always exhibit a positive covariance as is currently assumed for pelagic carbonates.

Applying modeling Results in designing a global tropospheric experiment

NASA Technical Reports Server (NTRS)

1982-01-01

A set of field experiments and advanced modeling studies which provide a strategy for a program of global tropospheric experiments was identified. An expanded effort to develop space applications for trospheric air quality monitoring and studies was recommended. The tropospheric ozone, carbon, nitrogen, and sulfur cycles are addressed. Stratospheric-tropospheric exchange is discussed. Fast photochemical processes in the free troposphere are considered.

Experimental and Numerical Investigation of Supercritical Carbon dioxide compact heat exchanger

NASA Astrophysics Data System (ADS)

Fatima, Roma; Kurizenga, Alan; Anderson, Mark; Ranjan, Devesh

2009-11-01

The use of super-critical carbon dioxide is gaining importance because of its use in Brayton cycles, to increase the cycle efficiency and reduce the initial capital investment, for high temperature energy conversion system. In order to reduce the capital cost, one improvement which was thought, is the use of compact, highly efficient, diffusion bonded heat exchangers for the regenerators. In this presentation we will focus on the experimental measurements of heat transfer and pressure drop characteristics within mini-channels. Two test section channel geometries were studied: a straight channel and a zigzag channel. Both configurations are 0.5m in length and constructed out of 316 stainless steel with a series of nine parallel 1.9mm semi-circular channels. The zigzag configuration has an angle of 115 degrees with an effective length of ˜0.58m. Heat transfer measurements were conducted for varying ranges of inlet temperatures, pressures, and mass flow rates. Numerical simulations have been performed using Fluent 12.0 to complement our experimental program. This is an ongoing program and we will be showing our recent progress we have made in last six months.

Congress examines administration's coal research priorities

NASA Astrophysics Data System (ADS)

Showstack, Randy

2011-10-01

While the Obama administration has proposed a shift in coal research funding to further emphasize carbon capture and sequestration (CCS) programs in its fiscal year (FY) 2012 budget request, Republicans and several witnesses at a 13 October hearing of a subcommittee of the House of Representatives' Committee on Science, Space, and Technology questioned those priorities, called for additional federal funding for coal research, and defended the use of coal as a major part of the U.S. energy sector. The administration's FY 2012 budget requests 291.4 million to fund the Department of Energy's (DOE) CCS and power systems program while zeroing out funding for DOE's fuels and power systems program (which includes funding for coal research) and shifting some of its line items to the CCS program. The FY 2011 continuing resolution has funded the fuels and power systems program at 400.2 million, including 142 million for carbon sequestration, 64.8 million for innovations for existing plants, and funding for other subprograms such as advanced integrated gasification combined cycle (52.9 million), fuel cells (49.8 million), and advanced research ($47.6 million).

Sulfur cycling in plays an important role in the development of Ocean Anoxic Events

NASA Astrophysics Data System (ADS)

Gomes, M. L.; Raven, M. R.; Fike, D. A.; Gill, B. C.; Johnston, D. T.

2017-12-01

Ocean Anoxic Events (OAEs) are major carbon cycle perturbations marked by enhanced organic carbon deposition in the marine realm and carbon isotope excursions in organic and inorganic carbon. Although not as severe as the "big five" mass extinctions, OAEs had dire consequences for marine ecosystems and thus influenced Mesozoic evolutionary patterns. Sulfur cycle reconstructions provide insight into the biogeochemical processes that played a role in the development of OAEs because the sulfur cycle is linked with the carbon and oxygen cycles. We present sulfur and oxygen isotope records from carbonate-associated sulfate from the Toarcian OAE that documents a positive sulfate-oxygen isotope excursion of +6‰, which is similar to the magnitude of the positive sulfur isotope excursion documented at the same site and other globally distributed sites. This high-resolution record allows us to explore temporal variability in the onset of the isotopic excursions: the onset of the positive sulfate-oxygen isotope excursion occurs at the same stratigraphic interval as the onset of the positive carbon isotope excursion and both precede the onset of the positive sulfate-sulfur isotope excursion. Because oxygen is rapidly recycled during oxidative sulfur cycling, changes in oxidative sulfur cycling affect oxygen isotope values of sulfate without impacting sulfur isotope values. Thus, the early onset of the sulfate-oxygen isotope excursion implies a change in oxidative sulfur cycling, which is likely due to a shoaling of the zone of sulfate reduction. We explore the consequences of sulfate reduction zone shoaling for organic carbon preservation. Specifically, the sulfurization of organic matter, which makes organic matter less susceptible to degradation, occurs more rapidly when the top of the zone of sulfate reduction is near or above the sediment water interface. Therefore, we suggest that the shoaling of the sulfate reduction zone locally changed pathways of oxidative sulfur cycling and enhanced organic carbon preservation. Given synchronous changes in similar, globally-distributed depositional environments, this impacted the global biogeochemical cycles of oxygen, carbon, and nutrients in ways that sustained decreased oxygen availability and influenced extinction patterns of marine organisms.

NASA/GSFC Research Activities for the Global Ocean Carbon Cycle: A Prospectus for the 21st Century

NASA Technical Reports Server (NTRS)

Gregg, W. W.; Behrenfield, M. J.; Hoge, F. E.; Esaias, W. E.; Huang, N. E.; Long, S. R.; McClain, C. R.

2000-01-01

There are increasing concerns that anthropogenic inputs of carbon dioxide into the Earth system have the potential for climate change. In response to these concerns, the GSFC Laboratory for Hydrospheric Processes has formed the Ocean Carbon Science Team (OCST) to contribute to greater understanding of the global ocean carbon cycle. The overall goals of the OCST are to: 1) detect changes in biological components of the ocean carbon cycle through remote sensing of biooptical properties, 2) refine understanding of ocean carbon uptake and sequestration through application of basic research results, new satellite algorithms, and improved model parameterizations, 3) develop and implement new sensors providing critical missing environmental information related to the oceanic carbon cycle and the flux of CO2 across the air-sea interface. The specific objectives of the OCST are to: 1) establish a 20-year time series of ocean color, 2) develop new remote sensing technologies, 3) validate ocean remote sensing observations, 4) conduct ocean carbon cycle scientific investigations directly related to remote sensing data, emphasizing physiological, empirical and coupled physical/biological models, satellite algorithm development and improvement, and analysis of satellite data sets. These research and mission objectives are intended to improve our understanding of global ocean carbon cycling and contribute to national goals by maximizing the use of remote sensing data.

Performance of 12Ah aerospace nickel-cadmium cells of design variable groups

NASA Astrophysics Data System (ADS)

Vasanth, K. L.

1985-12-01

The design variable program of NASA is a systematic approach to evaluate the performance of 12Ah aerospace nickel-cadmium cells of 9 important cell designs. These cells were life cycled in a Low-Earth Orbit (LEO) regime for 3 to 4 years. Representative cells taken from the design variable groups after different cycling periods have been examined. The results show that: (1) positive swelling and carbonate content in the electrolyte increases as a function of the number of cycles, (2) electrolyte distribution follows the order NEG greater than POS greater than SEP, 3) control and no PQ groups outperformed the rest of the groups and (4) the polypropylene group shows very heavy cadmium migration and poor performance.

Performance of 12Ah aerospace nickel-cadmium cells of design variable groups

NASA Technical Reports Server (NTRS)

Vasanth, K. L.

1985-01-01

The design variable program of NASA is a systematic approach to evaluate the performance of 12Ah aerospace nickel-cadmium cells of 9 important cell designs. These cells were life cycled in a Low-Earth Orbit (LEO) regime for 3 to 4 years. Representative cells taken from the design variable groups after different cycling periods have been examined. The results show that: (1) positive swelling and carbonate content in the electrolyte increases as a function of the number of cycles, (2) electrolyte distribution follows the order NEG greater than POS greater than SEP, 3) control and no PQ groups outperformed the rest of the groups and (4) the polypropylene group shows very heavy cadmium migration and poor performance.

Cyclic process for producing methane in a tubular reactor with effective heat removal

DOEpatents

Frost, Albert C.; Yang, Chang-Lee

1986-01-01

Carbon monoxide-containing gas streams are converted to methane by a cyclic, essentially two-step process in which said carbon monoxide is disproportionated to form carbon dioxide and active surface carbon deposited on the surface of a catalyst, and said carbon is reacted with steam to form product methane and by-product carbon dioxide. The exothermic heat of reaction generated in each step is effectively removed during each complete cycle so as to avoid a build up of heat from cycle-to-cycle, with particularly advantageous techniques being employed for fixed bed, tubular and fluidized bed reactor operations.

Integrated Assessment of Carbon Dioxide Removal

NASA Astrophysics Data System (ADS)

Rickels, W.; Reith, F.; Keller, D.; Oschlies, A.; Quaas, M. F.

2018-03-01

To maintain the chance of keeping the average global temperature increase below 2°C and to limit long-term climate change, removing carbon dioxide from the atmosphere (carbon dioxide removal, CDR) is becoming increasingly necessary. We analyze optimal and cost-effective climate policies in the dynamic integrated assessment model (IAM) of climate and the economy (DICE2016R) and investigate (1) the utilization of (ocean) CDR under different climate objectives, (2) the sensitivity of policies with respect to carbon cycle feedbacks, and (3) how well carbon cycle feedbacks are captured in the carbon cycle models used in state-of-the-art IAMs. Overall, the carbon cycle model in DICE2016R shows clear improvements compared to its predecessor, DICE2013R, capturing much better long-term dynamics and also oceanic carbon outgassing due to excess oceanic storage of carbon from CDR. However, this comes at the cost of a (too) tight short-term remaining emission budget, limiting the model suitability to analyze low-emission scenarios accurately. With DICE2016R, the compliance with the 2°C goal is no longer feasible without negative emissions via CDR. Overall, the optimal amount of CDR has to take into account (1) the emission substitution effect and (2) compensation for carbon cycle feedbacks.

Effect of Thermal Cycling on the Tensile Behavior of Polymer Composites Reinforced by Basalt and Carbon Fibers

NASA Astrophysics Data System (ADS)

Khalili, S. Mohammad Reza; Najafi, Moslem; Eslami-Farsani, Reza

2017-01-01

The aim of the present work was to investigate the effect of thermal cycling on the tensile behavior of three types of polymer-matrix composites — a phenolic resin reinforced with woven basalt fibers, woven carbon fibers, and hybrid basalt and carbon fibers — in an ambient environment. For this purpose, tensile tests were performed on specimens previously subjected to a certain number of thermal cycles. The ultimate tensile strength of the specimen reinforced with woven basalt fibers had by 5% after thermal cycling, but the strength of the specimen with woven carbon fibers had reduced to a value by 11% higher than that before thermal cycling.

Seeing the Carbon Cycle

ERIC Educational Resources Information Center

Drouin, Pamela; Welty, David J.; Repeta, Daniel; Engle-Belknap, Cheryl A.; Cramer, Catherine; Frashure, Kim; Chen, Robert

2006-01-01

In this article, the authors present a classroom experiment that was developed to introduce middle school learners to the carbon cycle. The experiment deals with transfer of CO[subscript 2] between liquid reservoirs and the effect CO[subscript 2] has on algae growth. It allows students to observe the influence of the carbon cycle on algae growth,…

40 CFR Table 4 to Subpart Ggg of... - Monitoring Requirements for Control Devices a

Code of Federal Regulations, 2011 CFR

2011-07-01

... monitoring device, and 1. Total regeneration stream mass or volumetric flow during carbon bed regeneration cycle(s) 1. For each regeneration cycle, record the total regeneration stream mass or volumetric flow. Carbon bed temperature monitoring device 2. Temperature of carbon bed after regeneration 2. For each...

40 CFR Table 4 to Subpart Ggg of... - Monitoring Requirements for Control Devices a

Code of Federal Regulations, 2012 CFR

2012-07-01

... monitoring device, and 1. Total regeneration stream mass or volumetric flow during carbon bed regeneration cycle(s) 1. For each regeneration cycle, record the total regeneration stream mass or volumetric flow. Carbon bed temperature monitoring device 2. Temperature of carbon bed after regeneration 2. For each...

40 CFR Table 4 to Subpart Ggg of... - Monitoring Requirements for Control Devices a

Code of Federal Regulations, 2010 CFR

2010-07-01

... monitoring device, and 1. Total regeneration stream mass or volumetric flow during carbon bed regeneration cycle(s) 1. For each regeneration cycle, record the total regeneration stream mass or volumetric flow. Carbon bed temperature monitoring device 2. Temperature of carbon bed after regeneration 2. For each...

40 CFR Table 3 to Subpart Ooo of... - Batch Process Vent Monitoring Requirements

Code of Federal Regulations, 2013 CFR

2013-07-01

...) temperature Continuous records as specified in § 63.1416(d). a Carbon adsorber a Total regeneration steam flow or nitrogen flow, or pressure (gauge or absolute) during carbon bed regeneration cycle(s), and Record the total regeneration steam flow or nitrogen flow, or pressure for each carbon bed regeneration cycle...

40 CFR Table 3 to Subpart Ooo of... - Batch Process Vent Monitoring Requirements

Code of Federal Regulations, 2014 CFR

2014-07-01

...) temperature Continuous records as specified in § 63.1416(d). a Carbon adsorber a Total regeneration steam flow or nitrogen flow, or pressure (gauge or absolute) during carbon bed regeneration cycle(s), and Record the total regeneration steam flow or nitrogen flow, or pressure for each carbon bed regeneration cycle...

pyhector: A Python interface for the simple climate model Hector

DOE PAGES

Willner, Sven N.; Hartin, Corinne; Gieseke, Robert

2017-04-01

Here, pyhector is a Python interface for the simple climate model Hector (Hartin et al. 2015) developed in C++. Simple climate models like Hector can, for instance, be used in the analysis of scenarios within integrated assessment models like GCAM1, in the emulation of complex climate models, and in uncertainty analyses. Hector is an open-source, object oriented, simple global climate carbon cycle model. Its carbon cycle consists of a one pool atmosphere, three terrestrial pools which can be broken down into finer biomes or regions, and four carbon pools in the ocean component. The terrestrial carbon cycle includes primary productionmore » and respiration fluxes. The ocean carbon cycle circulates carbon via a simplified thermohaline circulation, calculating air-sea fluxes as well as the marine carbonate system. The model input is time series of greenhouse gas emissions; as example scenarios for these the Pyhector package contains the Representative Concentration Pathways (RCPs)2.« less

Formulating Energy Policies Related to Fossil Fuel Use: Critical Uncertainties in the Global Carbon Cycle

DOE R&D Accomplishments Database

Post, W. M.; Dale, V. H.; DeAngelis, D. L.; Mann, L. K.; Mulholland, P. J.; O`Neill, R. V.; Peng, T. -H.; Farrell, M. P.

1990-02-01

The global carbon cycle is the dynamic interaction among the earth's carbon sources and sinks. Four reservoirs can be identified, including the atmosphere, terrestrial biosphere, oceans, and sediments. Atmospheric CO{sub 2} concentration is determined by characteristics of carbon fluxes among major reservoirs of the global carbon cycle. The objective of this paper is to document the knowns, and unknowns and uncertainties associated with key questions that if answered will increase the understanding of the portion of past, present, and future atmospheric CO{sub 2} attributable to fossil fuel burning. Documented atmospheric increases in CO{sub 2} levels are thought to result primarily from fossil fuel use and, perhaps, deforestation. However, the observed atmospheric CO{sub 2} increase is less than expected from current understanding of the global carbon cycle because of poorly understood interactions among the major carbon reservoirs.

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

Willner, Sven N.; Hartin, Corinne; Gieseke, Robert

Here, pyhector is a Python interface for the simple climate model Hector (Hartin et al. 2015) developed in C++. Simple climate models like Hector can, for instance, be used in the analysis of scenarios within integrated assessment models like GCAM1, in the emulation of complex climate models, and in uncertainty analyses. Hector is an open-source, object oriented, simple global climate carbon cycle model. Its carbon cycle consists of a one pool atmosphere, three terrestrial pools which can be broken down into finer biomes or regions, and four carbon pools in the ocean component. The terrestrial carbon cycle includes primary productionmore » and respiration fluxes. The ocean carbon cycle circulates carbon via a simplified thermohaline circulation, calculating air-sea fluxes as well as the marine carbonate system. The model input is time series of greenhouse gas emissions; as example scenarios for these the Pyhector package contains the Representative Concentration Pathways (RCPs)2.« less

A connection to deep groundwater alters ecosystem carbon fluxes and budgets: Example from a Costa Rican rainforest

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

Genereux, David P.; Nagy, Laura A.; Osburn, Christopher L.

Field studies of watershed carbon fluxes and budgets are critical for understanding the carbon cycle, but the role of deep regional groundwater is poorly known and field examples are lacking. Here we show that discharge of regional groundwater into a lowland Costa Rican rainforest has a major influence on ecosystem carbon fluxes. Furthermore, this influence is observable through chemical, isotopic, and flux signals in groundwater, surface water, and air. Not addressing the influence of regional groundwater in the field measurement program and data analysis would give a misleading impression of the overall carbon source or sink status of the rainforest.more » In quantifying a carbon budget with the traditional "small watershed" mass-balance approach, it would be critical at this site and likely many others to consider watershed inputs or losses associated with exchange between the ecosystem and the deeper hydrogeological system on which it sits.« less

A connection to deep groundwater alters ecosystem carbon fluxes and budgets: Example from a Costa Rican rainforest

DOE PAGES

Genereux, David P.; Nagy, Laura A.; Osburn, Christopher L.; ...

2013-05-28

Field studies of watershed carbon fluxes and budgets are critical for understanding the carbon cycle, but the role of deep regional groundwater is poorly known and field examples are lacking. Here we show that discharge of regional groundwater into a lowland Costa Rican rainforest has a major influence on ecosystem carbon fluxes. Furthermore, this influence is observable through chemical, isotopic, and flux signals in groundwater, surface water, and air. Not addressing the influence of regional groundwater in the field measurement program and data analysis would give a misleading impression of the overall carbon source or sink status of the rainforest.more » In quantifying a carbon budget with the traditional "small watershed" mass-balance approach, it would be critical at this site and likely many others to consider watershed inputs or losses associated with exchange between the ecosystem and the deeper hydrogeological system on which it sits.« less

The Second State of the Carbon Cycle Report: A Scientific Basis for Policy and Management Decisions

NASA Astrophysics Data System (ADS)

Birdsey, R.; Mayes, M. A.; Reed, S.; Najjar, R.; Romero-Lankao, P.

2017-12-01

The second "State of the Carbon Cycle of North America Report" (SOCCR-2) includes an overview of the North American carbon budget and future projections, the consequences of changes to the carbon budget, details of the carbon budget in major terrestrial and aquatic ecosystems (including coastal ocean waters), information about anthropogenic drivers, and implications for policy and carbon management. SOCCR-2 includes new focus areas such as soil carbon, arctic and boreal ecosystems, tribal lands, and greater emphasis on aquatic systems and the role of societal drivers and decision making on the carbon cycle. In addition, methane is considered to a greater extent than before. SOCCR-2 will contribute to the next U.S. National Climate Assessment, as well as providing information to support science-based management decisions and policies that include climate change mitigation and adaptation in Canada, the United States, and Mexico. Although the Report is still in the review process, preliminary findings indicate that North America is a net emitter of carbon dioxide and methane to the atmosphere, and that natural sinks offset about 25% of emitted carbon dioxide. Combustion of fossil fuels represents the largest source of emissions, but show a decreasing trend over the last decade and a lower share (20%) of the global total compared with the previous decade. Forests, soils, grasslands, and coastal oceans comprise the largest carbon sinks, while emissions from inland waters are a significant source of carbon dioxide. The Report also documents the lateral transfers of carbon among terrestrial ecosystems and from terrestrial to near-coastal ecosystems, to complete the carbon cycle accounting. Further, the Report explores the consequences of rising atmospheric carbon dioxide on terrestrial and oceanic systems, and the capacity of these systems to continue to act as carbon sinks based on the drivers of future carbon cycle changes, including carbon-climate feedbacks, atmospheric composition, nutrient availability, and human activity and management decisions. SOCCR-2 highlights key data gaps in carbon accounting frameworks, uncertainties in modeling and estimation approaches, and integrated frameworks for improving our understanding of the North American carbon cycle.

Nonlinear Interactions between Climate and Atmospheric Carbon Dioxide Drivers of Terrestrial and Marine Carbon Cycle Changes

NASA Astrophysics Data System (ADS)

Hoffman, F. M.; Randerson, J. T.; Moore, J. K.; Goulden, M.; Fu, W.; Koven, C.; Swann, A. L. S.; Mahowald, N. M.; Lindsay, K. T.; Munoz, E.

2017-12-01

Quantifying interactions between global biogeochemical cycles and the Earth system is important for predicting future atmospheric composition and informing energy policy. We applied a feedback analysis framework to three sets of Historical (1850-2005), Representative Concentration Pathway 8.5 (2006-2100), and its extension (2101-2300) simulations from the Community Earth System Model version 1.0 (CESM1(BGC)) to quantify drivers of terrestrial and ocean responses of carbon uptake. In the biogeochemically coupled simulation (BGC), the effects of CO2 fertilization and nitrogen deposition influenced marine and terrestrial carbon cycling. In the radiatively coupled simulation (RAD), the effects of rising temperature and circulation changes due to radiative forcing from CO2, other greenhouse gases, and aerosols were the sole drivers of carbon cycle changes. In the third, fully coupled simulation (FC), both the biogeochemical and radiative coupling effects acted simultaneously. We found that climate-carbon sensitivities derived from RAD simulations produced a net ocean carbon storage climate sensitivity that was weaker and a net land carbon storage climate sensitivity that was stronger than those diagnosed from the FC and BGC simulations. For the ocean, this nonlinearity was associated with warming-induced weakening of ocean circulation and mixing that limited exchange of dissolved inorganic carbon between surface and deeper water masses. For the land, this nonlinearity was associated with strong gains in gross primary production in the FC simulation, driven by enhancements in the hydrological cycle and increased nutrient availability. We developed and applied a nonlinearity metric to rank model responses and driver variables. The climate-carbon cycle feedback gain at 2300 was 42% higher when estimated from climate-carbon sensitivities derived from the difference between FC and BGC than when derived from RAD. We re-analyzed other CMIP5 model results to quantify the effects of such nonlinearities on their projected climate-carbon cycle feedback gains.

Current systematic carbon-cycle observations and the need for implementing a policy-relevant carbon observing system

Treesearch

P. Ciais; A. J. Dolman; A. Bombelli; R. Duren; A. Peregon; P. J. Rayner; C. Miller; N. Gobron; G. Kinderman; G. Marland; N. Gruber; F. Chevallier; R. J. Andres; G. Balsamo; L. Bopp; F.-M. Bréon; G. Broquet; R. Dargaville; T. J. Battin; A. Borges; H. Bovensmann; M. Buchwitz; J. Butler; J. G. Canadell; R. B. Cook; R. DeFries; R. Engelen; K. R. Gurney; C. Heinze; M. Heimann; A. Held; M. Henry; B. Law; S. Luyssaert; J. Miller; T. Moriyama; C. Moulin; R. B. Myneni; C. Nussli; M. Obersteiner; D. Ojima; Y. Pan; J.-D. Paris; S. L. Piao; B. Poulter; S. Plummer; S. Quegan; P. Raymond; M. Reichstein; L. Rivier; C. Sabine; D. Schimel; O. Tarasova; R. Valentini; R. Wang; G. van der Werf; D. Wickland; M. Williams; C. Zehner

2014-01-01

A globally integrated carbon observation and analysis system is needed to improve the fundamental understanding of the global carbon cycle, to improve our ability to project future changes, and to verify the effectiveness of policies aiming to reduce greenhouse gas emissions and increase carbon sequestration. Building an integrated carbon observation system requires...

Reducing Demand through Efficiency and Services: Impacts and Opportunities in Buildings Sector (Carbon Cycle 2.0)

ScienceCinema

Piette, Mary Ann

2018-05-03

Mary Ann Piette, Deputy of LBNL's Building Technologies Department and Director of the Demand Response Research Center, speaks at the Carbon Cycle 2.0 kick-off symposium Feb. 2, 2010. We emit more carbon into the atmosphere than natural processes are able to remove - an imbalance with negative consequences. Carbon Cycle 2.0 is a Berkeley Lab initiative to provide the science needed to restore this balance by integrating the Labs diverse research activities and delivering creative solutions toward a carbon-neutral energy future.

Reducing Demand through Efficiency and Services: Impacts and Opportunities in Buildings Sector (Carbon Cycle 2.0)

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

Piette, Mary Ann

Mary Ann Piette, Deputy of LBNL's Building Technologies Department and Director of the Demand Response Research Center, speaks at the Carbon Cycle 2.0 kick-off symposium Feb. 2, 2010. We emit more carbon into the atmosphere than natural processes are able to remove - an imbalance with negative consequences. Carbon Cycle 2.0 is a Berkeley Lab initiative to provide the science needed to restore this balance by integrating the Labs diverse research activities and delivering creative solutions toward a carbon-neutral energy future.

Solar Thermochemical Energy Storage Through Carbonation Cycles of SrCO3/SrO Supported on SrZrO3.

PubMed

Rhodes, Nathan R; Barde, Amey; Randhir, Kelvin; Li, Like; Hahn, David W; Mei, Renwei; Klausner, James F; AuYeung, Nick

2015-11-01

Solar thermochemical energy storage has enormous potential for enabling cost-effective concentrated solar power (CSP). A thermochemical storage system based on a SrO/SrCO3 carbonation cycle offers the ability to store and release high temperature (≈1200 °C) heat. The energy density of SrCO3/SrO systems supported by zirconia-based sintering inhibitors was investigated for 15 cycles of exothermic carbonation at 1150 °C followed by decomposition at 1235 °C. A sample with 40 wt % of SrO supported by yttria-stabilized zirconia (YSZ) shows good energy storage stability at 1450 MJ m(-3) over fifteen cycles at the same cycling temperatures. After further testing over 45 cycles, a decrease in energy storage capacity to 1260 MJ m(-3) is observed during the final cycle. The decrease is due to slowing carbonation kinetics, and the original value of energy density may be obtained by lengthening the carbonation steps. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The decadal state of the terrestrial carbon cycle: Global retrievals of terrestrial carbon allocation, pools, and residence times

PubMed Central

Bloom, A. Anthony; Exbrayat, Jean-François; van der Velde, Ivar R.; Feng, Liang; Williams, Mathew

2016-01-01

The terrestrial carbon cycle is currently the least constrained component of the global carbon budget. Large uncertainties stem from a poor understanding of plant carbon allocation, stocks, residence times, and carbon use efficiency. Imposing observational constraints on the terrestrial carbon cycle and its processes is, therefore, necessary to better understand its current state and predict its future state. We combine a diagnostic ecosystem carbon model with satellite observations of leaf area and biomass (where and when available) and soil carbon data to retrieve the first global estimates, to our knowledge, of carbon cycle state and process variables at a 1° × 1° resolution; retrieved variables are independent from the plant functional type and steady-state paradigms. Our results reveal global emergent relationships in the spatial distribution of key carbon cycle states and processes. Live biomass and dead organic carbon residence times exhibit contrasting spatial features (r = 0.3). Allocation to structural carbon is highest in the wet tropics (85–88%) in contrast to higher latitudes (73–82%), where allocation shifts toward photosynthetic carbon. Carbon use efficiency is lowest (0.42–0.44) in the wet tropics. We find an emergent global correlation between retrievals of leaf mass per leaf area and leaf lifespan (r = 0.64–0.80) that matches independent trait studies. We show that conventional land cover types cannot adequately describe the spatial variability of key carbon states and processes (multiple correlation median = 0.41). This mismatch has strong implications for the prediction of terrestrial carbon dynamics, which are currently based on globally applied parameters linked to land cover or plant functional types. PMID:26787856

Potential increases in natural disturbance rates could offset forest management impacts on ecosystem carbon stocks

USGS Publications Warehouse

Bradford, John B.; Jensen, Nicholas R.; Domke, Grant M.; D’Amato, Anthony W.

2013-01-01

Forested ecosystems contain the majority of the world’s terrestrial carbon, and forest management has implications for regional and global carbon cycling. Carbon stored in forests changes with stand age and is affected by natural disturbance and timber harvesting. We examined how harvesting and disturbance interact to influence forest carbon stocks over the Superior National Forest, in northern Minnesota. Forest inventory data from the USDA Forest Service, Forest Inventory and Analysis program were used to characterize current forest age structure and quantify the relationship between age and carbon stocks for eight forest types. Using these findings, we simulated the impact of alternative management scenarios and natural disturbance rates on forest-wide terrestrial carbon stocks over a 100-year horizon. Under low natural mortality, forest-wide total ecosystem carbon stocks increased when 0% or 40% of planned harvests were implemented; however, the majority of forest-wide carbon stocks decreased with greater harvest levels and elevated disturbance rates. Our results suggest that natural disturbance has the potential to exert stronger influence on forest carbon stocks than timber harvesting activities and that maintaining carbon stocks over the long-term may prove difficult if disturbance frequency increases in response to climate change.

Decadally cycling soil carbon is more sensitive to warming than faster-cycling soil carbon.

PubMed

Lin, Junjie; Zhu, Biao; Cheng, Weixin

2015-12-01

The response of soil organic carbon (SOC) pools to globally rising surface temperature crucially determines the feedback between climate change and the global carbon cycle. However, there is a lack of studies investigating the temperature sensitivity of decomposition for decadally cycling SOC which is the main component of total soil carbon stock and the most relevant to global change. We tackled this issue using two decadally (13) C-labeled soils and a much improved measuring system in a long-term incubation experiment. Results indicated that the temperature sensitivity of decomposition for decadally cycling SOC (>23 years in one soil and >55 years in the other soil) was significantly greater than that for faster-cycling SOC (<23 or 55 years) or for the entire SOC stock. Moreover, decadally cycling SOC contributed substantially (35-59%) to the total CO2 loss during the 360-day incubation. Overall, these results indicate that the decomposition of decadally cycling SOC is highly sensitive to temperature change, which will likely make this large SOC stock vulnerable to loss by global warming in the 21st century and beyond. © 2015 John Wiley & Sons Ltd.

Understanding future emissions from low-carbon power systems by integration of life-cycle assessment and integrated energy modelling

NASA Astrophysics Data System (ADS)

Pehl, Michaja; Arvesen, Anders; Humpenöder, Florian; Popp, Alexander; Hertwich, Edgar G.; Luderer, Gunnar

2017-12-01

Both fossil-fuel and non-fossil-fuel power technologies induce life-cycle greenhouse gas emissions, mainly due to their embodied energy requirements for construction and operation, and upstream CH4 emissions. Here, we integrate prospective life-cycle assessment with global integrated energy-economy-land-use-climate modelling to explore life-cycle emissions of future low-carbon power supply systems and implications for technology choice. Future per-unit life-cycle emissions differ substantially across technologies. For a climate protection scenario, we project life-cycle emissions from fossil fuel carbon capture and sequestration plants of 78-110 gCO2eq kWh-1, compared with 3.5-12 gCO2eq kWh-1 for nuclear, wind and solar power for 2050. Life-cycle emissions from hydropower and bioenergy are substantial (˜100 gCO2eq kWh-1), but highly uncertain. We find that cumulative emissions attributable to upscaling low-carbon power other than hydropower are small compared with direct sectoral fossil fuel emissions and the total carbon budget. Fully considering life-cycle greenhouse gas emissions has only modest effects on the scale and structure of power production in cost-optimal mitigation scenarios.

Science and Observation Recommendations for Future NASA Carbon Cycle Research

NASA Technical Reports Server (NTRS)

McClain, Charles R.; Collatz, G. J.; Kawa, S. R.; Gregg, W. W.; Gervin, J. C.; Abshire, J. B.; Andrews, A. E.; Behrenfeld, M. J.; Demaio, L. D.; Knox, R. G.

2002-01-01

Between October 2000 and June 2001, an Agency-wide planning, effort was organized by elements of NASA Goddard Space Flight Center (GSFC) to define future research and technology development activities. This planning effort was conducted at the request of the Associate Administrator of the Office of Earth Science (Code Y), Dr. Ghassem Asrar, at NASA Headquarters (HQ). The primary points of contact were Dr. Mary Cleave, Deputy Associate Administrator for Advanced Planning at NASA HQ (Headquarters) and Dr. Charles McClain of the Office of Global Carbon Studies (Code 970.2) at GSFC. During this period, GSFC hosted three workshops to define the science requirements and objectives, the observational and modeling requirements to meet the science objectives, the technology development requirements, and a cost plan for both the science program and new flight projects that will be needed for new observations beyond the present or currently planned. The plan definition process was very intensive as HQ required the final presentation package by mid-June 2001. This deadline was met and the recommendations were ultimately refined and folded into a broader program plan, which also included climate modeling, aerosol observations, and science computing technology development, for contributing to the President's Climate Change Research Initiative. This technical memorandum outlines the process and recommendations made for cross-cutting carbon cycle research as presented in June. A separate NASA document outlines the budget profiles or cost analyses conducted as part of the planning effort.

Modeling carbon cycle process of soil profile in Loess Plateau of China

NASA Astrophysics Data System (ADS)

Yu, Y.; Finke, P.; Guo, Z.; Wu, H.

2011-12-01

SoilGen2 is a process-based model, which could reconstruct soil formation under various climate conditions, parent materials, vegetation types, slopes, expositions and time scales. Both organic and inorganic carbon cycle processes could be simulated, while the later process is important in carbon cycle of arid and semi-arid regions but seldom being studied. After calibrating parameters of dust deposition rate and segments depth affecting elements transportation and deposition in the profile, modeling results after 10000 years were confronted with measurements of two soil profiles in loess plateau of China, The simulated trends of organic carbon and CaCO3 in the profile are similar to measured values. Relative sensitivity analysis for carbon cycle process have been done and the results show that the change of organic carbon in long time scale is more sensitive to precipitation, temperature, plant carbon input and decomposition parameters (decomposition rate of humus, ratio of CO2/(BIO+HUM), etc.) in the model. As for the inorganic carbon cycle, precipitation and potential evaporation are important for simulation quality, while the leaching and deposition of CaCO3 are not sensitive to pCO2 and temperature of atmosphere.

40 CFR Table 7 to Subpart U of... - Operating Parameters for Which Monitoring Levels Are Required To Be Established for Continuous...

Code of Federal Regulations, 2012 CFR

2012-07-01

.... Condenser Exit temperature Maximum temperature. Carbon adsorber Total regeneration steam flow or nitrogen flow, or pressure (gauge or absolute) a during carbon bed regeneration cycle; and temperature of the carbon bed after regeneration (and within 15 minutes of completing any cooling cycle(s)) Maximum flow or...

40 CFR Table 7 to Subpart Ppp of... - Process Vents From Continuous Unit Operations-Monitoring, Recordkeeping, and Reporting Requirements

Code of Federal Regulations, 2010 CFR

2010-07-01

... absorbent is used. Condenser Exit temperature Maximum temperature. Carbon adsorber Total regeneration stream mass or volumetric flow during carbon bed regeneration cycle; and temperature of the carbon bed after regeneration (and within 15 minutes of completing any cooling cycle(s)) Maximum mass or volumetric flow; and...

40 CFR Table 5 to Subpart Ppp of... - Process Vents From Batch Unit Operations-Monitoring, Recordkeeping, and Reporting Requirements

Code of Federal Regulations, 2011 CFR

2011-07-01

... Carbon Adsorber f Total regeneration stream mass or volumetric flow during carbon bed regeneration cycle(s), and 1. Record of total regeneration stream mass or volumetric flow for each carbon bed regeneration cycle.2. Record and report the total regeneration stream mass or volumetric flow during each...

40 CFR Table 7 to Subpart U of... - Operating Parameters for Which Monitoring Levels Are Required To Be Established for Continuous...

Code of Federal Regulations, 2014 CFR

2014-07-01

.... Condenser Exit temperature Maximum temperature. Carbon adsorber Total regeneration steam flow or nitrogen flow, or pressure (gauge or absolute) a during carbon bed regeneration cycle; and temperature of the carbon bed after regeneration (and within 15 minutes of completing any cooling cycle(s)) Maximum flow or...

40 CFR Table 7 to Subpart Ppp of... - Process Vents From Continuous Unit Operations-Monitoring, Recordkeeping, and Reporting Requirements

Code of Federal Regulations, 2012 CFR

2012-07-01

... absorbent is used. Condenser Exit temperature Maximum temperature. Carbon adsorber Total regeneration stream mass or volumetric flow during carbon bed regeneration cycle; and temperature of the carbon bed after regeneration (and within 15 minutes of completing any cooling cycle(s)) Maximum mass or volumetric flow; and...

40 CFR Table 5 to Subpart Ppp of... - Process Vents From Batch Unit Operations-Monitoring, Recordkeeping, and Reporting Requirements

Code of Federal Regulations, 2012 CFR

2012-07-01

... Carbon Adsorber f Total regeneration stream mass or volumetric flow during carbon bed regeneration cycle(s), and 1. Record of total regeneration stream mass or volumetric flow for each carbon bed regeneration cycle.2. Record and report the total regeneration stream mass or volumetric flow during each...

40 CFR Table 5 to Subpart Ppp of... - Process Vents From Batch Unit Operations-Monitoring, Recordkeeping, and Reporting Requirements

Code of Federal Regulations, 2010 CFR

2010-07-01

... Carbon Adsorber f Total regeneration stream mass or volumetric flow during carbon bed regeneration cycle(s), and 1. Record of total regeneration stream mass or volumetric flow for each carbon bed regeneration cycle.2. Record and report the total regeneration stream mass or volumetric flow during each...

40 CFR Table 7 to Subpart Ppp of... - Process Vents From Continuous Unit Operations-Monitoring, Recordkeeping, and Reporting Requirements

Code of Federal Regulations, 2011 CFR

2011-07-01

... absorbent is used. Condenser Exit temperature Maximum temperature. Carbon adsorber Total regeneration stream mass or volumetric flow during carbon bed regeneration cycle; and temperature of the carbon bed after regeneration (and within 15 minutes of completing any cooling cycle(s)) Maximum mass or volumetric flow; and...

40 CFR Table 7 to Subpart U of... - Operating Parameters for Which Monitoring Levels Are Required To Be Established for Continuous...

Code of Federal Regulations, 2010 CFR

2010-07-01

.... Condenser Exit temperature Maximum temperature. Carbon adsorber Total regeneration steam flow or nitrogen flow, or pressure (gauge or absolute) a during carbon bed regeneration cycle; and temperature of the carbon bed after regeneration (and within 15 minutes of completing any cooling cycle(s)) Maximum flow or...

40 CFR Table 7 to Subpart U of... - Operating Parameters for Which Monitoring Levels Are Required To Be Established for Continuous...

Code of Federal Regulations, 2011 CFR

2011-07-01

.... Condenser Exit temperature Maximum temperature. Carbon adsorber Total regeneration steam flow or nitrogen flow, or pressure (gauge or absolute) a during carbon bed regeneration cycle; and temperature of the carbon bed after regeneration (and within 15 minutes of completing any cooling cycle(s)) Maximum flow or...

40 CFR Table 7 to Subpart U of... - Operating Parameters for Which Monitoring Levels Are Required To Be Established for Continuous...

Code of Federal Regulations, 2013 CFR

2013-07-01

.... Condenser Exit temperature Maximum temperature. Carbon adsorber Total regeneration steam flow or nitrogen flow, or pressure (gauge or absolute) a during carbon bed regeneration cycle; and temperature of the carbon bed after regeneration (and within 15 minutes of completing any cooling cycle(s)) Maximum flow or...

Nitrogen attenuation of terrestrial carbon cycle response to global environmental factors

Treesearch

Atul Jain; Xiaojuan Yang; Haroon Kheshgi; A. David McGuire; Wilfred Post; David Kicklighter

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...

Pervasive drought legacies in forest ecosystems and their implications for carbon cycle models

Treesearch

W. R. L. Anderegg; C. Schwalm; F. Biondi; J. J. Camarero; G. Koch; M. Litvak; K. Ogle; J. D. Shaw; E. Shevliakova; A. P. Williams; A. Wolf; E. Ziaco; S. Pacala

2015-01-01

The impacts of climate extremes on terrestrial ecosystems are poorly understood but important for predicting carbon cycle feedbacks to climate change. Coupled climate-carbon cycle models typically assume that vegetation recovery from extreme drought is immediate and complete, which conflicts with the understanding of basic plant physiology. We examined the recovery of...

A program in global biology. [biota-environment interaction important to life

NASA Technical Reports Server (NTRS)

Mooneyhan, D. W.

1983-01-01

NASA's Global Biology Research Program and its goals for greater understanding of planetary biological processes are discussed. Consideration is given to assessing major pathways and rates of exchange of elements such as carbon and nitrogen, extrapolating local rates of anaerobic activities, determining exchange rates of ocean nutrients, and developing models for the global cycles of carbon, nitrogen, sulfur, and phosphorus. Satellites and sensors operating today are covered: the Nimbus, NOAA, and Landsat series. Block diagrams of the software and hardware for a typical ground data processing and analysis system are provided. Samples of the surface cover data achieved with the Advanced Very High Resolution Radiometer, the Multispectral Scanner, and the Thematic Mapper are presented, as well as a productive capacity model for coastal wetlands. Finally, attention is given to future goals, their engineering requirements, and the necessary data analysis system.

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

NASA Astrophysics Data System (ADS)

Zeebe, R. E.

2011-06-01

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

Towards a more complete SOCCR: Establishing a Coastal Carbon Data Network

NASA Astrophysics Data System (ADS)

Pidgeon, E.; Howard, J.; Tang, J.; Kroeger, K. D.; Windham-Myers, L.

2015-12-01

The 2007 State of the Carbon Cycle Report (SOCCR) was highly influential in ensuring components of the carbon cycle were accounted for in national policy and related management. However, while SOCCR detailed the significance of North American coastal wetlands, it was not until recently that leading governments began to fully recognized these ecosystems for their carbon sequestration and storage capacity and hence the significant role coastal ecosystems can play in GHG emission reductions strategies, offset mechanisms, coastal management strategies and climate mitigation policy. The new attention on coastal carbon systems has exposed limitations in terms of data availability and data quality, as well as insufficient knowledge of coastal carbon distributions, characteristics and coastal carbon cycle processes. In addition to restricting scientific progress, lack of comprehensive, comparable, and quality-controlled coastal carbon data is hindering progress towards carbon based conservation and coastal management. To directly address those limitations, we are developing a Global Science and Data Network for Coastal "Blue" Carbon, with support from the Carbon Cycle Interagency Working Group. Goals include: • Improving basic and applied science on carbon and GHG cycling in vegetated coastal ecosystems; • Supporting a coastal carbon and associated GHG data archive for use by the science community, coastal and climate practitioners and other data users; • Building the capacity of coastal carbon stakeholders globally to collect and interpret high quality coastal carbon science and data; • Providing a forum and mechanism to promote exchange and collaboration between scientists and coastal carbon data users globally; and • Outreach activities to ensure the best available data are globally accessible and that science is responsive to the needs of coastal managers and policy-makers.

The impact of single-tree selection and clearcut harvest on selected biochemical soil health indicators at the Missouri Forest Ecosystem Program and Long Term Soil Productivity sites in the Missouri Ozarks

USDA-ARS?s Scientific Manuscript database

The objective of this study was to evaluate carbon, nitrogen, sulfur and phosphorus (CNSP) cycling and to determine potential biochemical soil health indicators applicable to timber harvesting in the Missouri Ozarks. Soil samples were collected from the Missouri Forest Ecosystem Project (MOFEP) and ...

Carbon corrosion in PEM fuel cells during drive cycle operation

DOE PAGES

Borup, Rodney L.; Papadias, D. D.; Mukundan, Rangachary; ...

2015-09-14

One of the major contributors to degradation involves the electrocatalyst, including the corrosion of the carbons used as catalyst supports, which leads to changes in the catalyst layer structure. We have measured and quantified carbon corrosion during drive cycle operation and as a variation of the upper and lower potential limits used during drive cycle operation. The amount of carbon corrosion is exacerbated by the voltage cycling inherent in the drive cycle compared with constant potential operation. The potential gap between upper and lower potentials appears to be more important than the absolute operating potentials in the normal operating potentialmore » regime (0.40V to 0.95V) as changes in the measured carbon corrosion are similar when the upper potential was lower compared to raising the lower potential. Catalyst layer thinning was observed during the simulated drive cycle operation which had an associated decrease in catalyst layer porosity. This catalyst layer thinning is not due solely to carbon corrosion, although carbon corrosion likely plays a role; much of this thinning must be from compaction of the material in the catalyst layer. As a result, the decrease in catalyst layer porosity leads to additional performance losses due to mass transport losses.« less

The biological carbon pump in the ocean: Reviewing model representations and its feedbacks on climate perturbations.

NASA Astrophysics Data System (ADS)

Hülse, Dominik; Arndt, Sandra; Ridgwell, Andy; Wilson, Jamie

2016-04-01

The ocean-sediment system, as the biggest carbon reservoir in the Earth's carbon cycle, plays a crucial role in regulating atmospheric carbon dioxide concentrations and climate. Therefore, it is essential to constrain the importance of marine carbon cycle feedbacks on global warming and ocean acidification. Arguably, the most important single component of the ocean's carbon cycle is the so-called "biological carbon pump". It transports carbon that is fixed in the light-flooded surface layer of the ocean to the deep ocean and the surface sediment, where it is degraded/dissolved or finally buried in the deep sediments. Over the past decade, progress has been made in understanding different factors that control the efficiency of the biological carbon pump and their feedbacks on the global carbon cycle and climate (i.e. ballasting = ocean acidification feedback; temperature dependant organic matter degradation = global warming feedback; organic matter sulphurisation = anoxia/euxinia feedback). Nevertheless, many uncertainties concerning the interplay of these processes and/or their relative significance remain. In addition, current Earth System Models tend to employ empirical and static parameterisations of the biological pump. As these parametric representations are derived from a limited set of present-day observations, their ability to represent carbon cycle feedbacks under changing climate conditions is limited. The aim of my research is to combine past carbon cycling information with a spatially resolved global biogeochemical model to constrain the functioning of the biological pump and to base its mathematical representation on a more mechanistic approach. Here, I will discuss important aspects that control the efficiency of the ocean's biological carbon pump, review how these processes of first order importance are mathematically represented in existing Earth system Models of Intermediate Complexity (EMIC) and distinguish different approaches to approximate biogeochemical processes in the sediments. The performance of the respective mathematical representations in constraining the importance of carbon pump feedbacks on marine biogeochemical dynamics is then compared and evaluated under different extreme climate scenarios (e.g. OAE2, Eocene) using the Earth system model 'GENIE' and proxy records. The compiled mathematical descriptions and the model results underline the lack of a complete and mechanistic framework to represent the short-term carbon cycle in most EMICs which seriously limits the ability of these models to constrain the response of the ocean's carbon cycle to past and in particular future climate change. In conclusion, this presentation will critically evaluate the approaches currently used in marine biogeochemical modelling and outline key research directions concerning model development in the future.

Thermal Cycling of Thermal Control Paints on Carbon-Carbon and Carbon-Polyimide Composites

NASA Technical Reports Server (NTRS)

Jaworske, Donald A.

2006-01-01

Carbon-carbon composites and carbon-polyimide composites are being considered for space radiator applications owing to their light weight and high thermal conductivity. For those radiator applications where sunlight will impinge on the surface, it will be necessary to apply a white thermal control paint to minimize solar absorptance and enhance infrared emittance. Several currently available white thermal control paints were applied to candidate carbon-carbon and carbon-polyimide composites and were subjected to vacuum thermal cycling in the range of -100 C to +277 C. The optical properties of solar absorptance and infrared emittance were evaluated before and after thermal cycling. In addition, adhesion of the paints was evaluated utilizing a tape test. The test matrix included three composites: resin-derived carbon-carbon and vapor infiltrated carbon-carbon, both reinforced with pitch-based P-120 graphite fibers, and a polyimide composite reinforced with T-650 carbon fibers, and three commercially available white thermal control paints: AZ-93, Z-93-C55, and YB-71P.

Tracking heterotrophic and autotrophic carbon cycling by magnetotactic bacteria in freshwater sediments using DNA stable isotope probing

NASA Astrophysics Data System (ADS)

Kürşat Coşkun, Ömer; Roud, Sophie; He, Kuang; Petersen, Nikolai; Gilder, Stuart; Orsi, William D.

2017-04-01

Magnetotactic bacteria (MTB) are diverse, widespread, motile prokaryotes which biomineralize nanosize magnetic minerals, either magnetite or gregite, under highly conserved genetic control and have magnetotaxis to align their position in aquatic environment according to Earth's magnetic field. They play important roles on some geobiological cycle of important minerals such as iron, sulphur, nitrogen and carbon. Yet, to date, their importance in carbon cycle and carbon source in their natural environment have not been previously studied. In this study, we focused on freshwater benthic carbon cycling of MTB and total bacteria using DNA stable isotope probing (DNA-SIP) technique coupled with quantitative PCR (qPCR). Pond sediments from Unterlippach (Germany) were amended with 13C-labelled sodium bicarbonate and 13C-labelled organic matter, and incubated in the dark over a two week time period. Applying separate qPCR assays specific for total bacteria and MTB, respectively, allowed us to estimate the contribution of MTB to total heterotrophic and autotrophic carbon cycling via DNA-SIP. After one week, there was a slight degree of autotrophic activity which increased markedly after two weeks. Comparing total DNA to the qPCR data revealed that changes in the buoyant density of DNA was due mainly to autotrophic bacterial production. DNA-SIP also identified heterotrophic utilization of 13C-labelled organic matter by MTB after 1 week. The qPCR data also allowed us to estimate uptake rates based on the incubation times for heterotrophic and autotrophic MTB. High-throughput DNA sequencing of 16S rRNA genes showed that most of the MTB involved in carbon cycling were related to the Magnetococcus genus. This study sheds light on the carbon sources for MTB in a natural environment and helps unravel their ecological role in the carbon cycle.

Atmospheric carbon dioxide and the global carbon cycle

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

Trabalka, J R

1985-12-01

This state-of-the-art volume presents discussions on the global cycle of carbon, the dynamic balance among global atmospheric CO2 sources and sinks. Separate abstracts have been prepared for the individual papers. (ACR)

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

Marrocco, M.

The Ohio Power Company`s Tidd Pressurized Fluidized Bed Combined Cycle (PFBC) program continues to be the only operating PFBC demonstration program in the nation. The 70 MWe Tidd Demonstration Plant is a Round 1 Clean Coal Technology Project constructed to demonstrate the viability of PFBC combined cycle technology. The plant is now in Rs fourth year of operation. The technology has clearly demonstrated Rs ability to achieve sulfur capture of greater than 95%. The calcium to sulfur molar ratios have been demonstrated to exceed original projections. Unit availability has steadily increased and has been demonstrated to be competitive with othermore » technologies. The operating experience of the first forty-four months of testing has moved the PFBC process from a {open_quotes}promising technology{close_quotes} to available, proven option for efficient, environmentally acceptable base load generation. Funding for the $210 million program is provided by Ohio Power Company, The U.S. Department of Energy, The Ohio Coal Development Office, and the PFBC process vendors - Asea Brown Boveri Carbon (ABBC) and Babcock and Wilcox (B&W).« less

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...

40 CFR Table 5 to Subpart Ppp of... - Process Vents From Batch Unit Operations-Monitoring, Recordkeeping, and Reporting Requirements

Code of Federal Regulations, 2013 CFR

2013-07-01

... collected—PR. d,e Carbon Adsorber f Total regeneration stream mass or volumetric flow during carbon bed regeneration cycle(s), and 1. Record of total regeneration stream mass or volumetric flow for each carbon bed regeneration cycle.2. Record and report the total regeneration stream mass or volumetric flow during each...

40 CFR Table 6 to Subpart Ppp of... - Process Vents From Continuous Unit Operations-Monitoring, Recordkeeping, and Reporting Requirements

Code of Federal Regulations, 2014 CFR

2014-07-01

... operating—PR. d e Carbon Adsorber f Total regeneration stream mass or volumetric flow during carbon bed regeneration cycle(s), and 1. Record of total regeneration stream mass or volumetric flow for each carbon bed regeneration cycle.2. Record and report the total regeneration stream mass or volumetric flow during each...

40 CFR Table 6 to Subpart Ppp of... - Process Vents From Continuous Unit Operations-Monitoring, Recordkeeping, and Reporting Requirements

Code of Federal Regulations, 2010 CFR

2010-07-01

... temperature established in the NCS or operating—PR. d,e Carbon Adsorber f Total regeneration stream mass or volumetric flow during carbon bed regeneration cycle(s), and 1. Record of total regeneration stream mass or volumetric flow for each carbon bed regeneration cycle.2. Record and report the total regeneration stream...

40 CFR Table 7 to Subpart G of... - Transfer Operations-Monitoring, Recordkeeping, and Reporting Requirements for Complying With 98...

Code of Federal Regulations, 2013 CFR

2013-07-01

... collected f—PR. Carbon adsorber h Total regeneration stream mass or volumetric or volumetric flow during carbon bed regeneration cycle(s) [63.127(b)(3)], and 1. Record of total regeneration stream mass or volumetric flow for each carbon bed regeneration cycle.2. Record and report the total regeneration stream...

40 CFR Table 4 to Subpart G of... - Process Vents-Monitoring, Recordkeeping, and Reporting Requirements For Maintaining a TRE Index...

Code of Federal Regulations, 2014 CFR

2014-07-01

... NCS or operating permit—PR. Carbon adsorber d Total regeneration stream mass or volumetric flow during carbon bed regeneration cycle(s) [63.114(b)(3)], and 1. Record of total regeneration stream mass or volumetric flow for each carbon bed regeneration cycle.2. Record and report the total regeneration stream...

40 CFR Table 7 to Subpart G of... - Transfer Operations-Monitoring, Recordkeeping, and Reporting Requirements for Complying With 98...

Code of Federal Regulations, 2012 CFR

2012-07-01

... collected f—PR. Carbon adsorber h Total regeneration stream mass or volumetric or volumetric flow during carbon bed regeneration cycle(s) [63.127(b)(3)], and 1. Record of total regeneration stream mass or volumetric flow for each carbon bed regeneration cycle.2. Record and report the total regeneration stream...

40 CFR Table 6 to Subpart Ppp of... - Process Vents From Continuous Unit Operations-Monitoring, Recordkeeping, and Reporting Requirements

Code of Federal Regulations, 2011 CFR

2011-07-01

... temperature established in the NCS or operating—PR. d,e Carbon Adsorber f Total regeneration stream mass or volumetric flow during carbon bed regeneration cycle(s), and 1. Record of total regeneration stream mass or volumetric flow for each carbon bed regeneration cycle.2. Record and report the total regeneration stream...

40 CFR Table 4 to Subpart G of... - Process Vents-Monitoring, Recordkeeping, and Reporting Requirements For Maintaining a TRE Index...

Code of Federal Regulations, 2013 CFR

2013-07-01

... NCS or operating permit—PR. Carbon adsorber d Total regeneration stream mass or volumetric flow during carbon bed regeneration cycle(s) [63.114(b)(3)], and 1. Record of total regeneration stream mass or volumetric flow for each carbon bed regeneration cycle.2. Record and report the total regeneration stream...

40 CFR Table 4 to Subpart G of... - Process Vents-Monitoring, Recordkeeping, and Reporting Requirements For Maintaining a TRE Index...

Code of Federal Regulations, 2010 CFR

2010-07-01

... NCS or operating permit—PR. Carbon adsorber d Total regeneration stream mass or volumetric flow during carbon bed regeneration cycle(s) [63.114(b)(3)], and 1. Record of total regeneration stream mass or volumetric flow for each carbon bed regeneration cycle.2. Record and report the total regeneration stream...

40 CFR Table 7 to Subpart G of... - Transfer Operations-Monitoring, Recordkeeping, and Reporting Requirements for Complying With 98...

Code of Federal Regulations, 2011 CFR

2011-07-01

... collected f—PR. Carbon adsorber h Total regeneration stream mass or volumetric or volumetric flow during carbon bed regeneration cycle(s) [63.127(b)(3)], and 1. Record of total regeneration stream mass or volumetric flow for each carbon bed regeneration cycle.2. Record and report the total regeneration stream...

40 CFR Table 5 to Subpart Ppp of... - Process Vents From Batch Unit Operations-Monitoring, Recordkeeping, and Reporting Requirements

Code of Federal Regulations, 2014 CFR

2014-07-01

... collected—PR. d e Carbon Adsorber f Total regeneration stream mass or volumetric flow during carbon bed regeneration cycle(s), and 1. Record of total regeneration stream mass or volumetric flow for each carbon bed regeneration cycle.2. Record and report the total regeneration stream mass or volumetric flow during each...

40 CFR Table 7 to Subpart G of... - Transfer Operations-Monitoring, Recordkeeping, and Reporting Requirements for Complying With 98...

Code of Federal Regulations, 2014 CFR

2014-07-01

... collected f—PR. Carbon adsorber h Total regeneration stream mass or volumetric or volumetric flow during carbon bed regeneration cycle(s) [63.127(b)(3)], and 1. Record of total regeneration stream mass or volumetric flow for each carbon bed regeneration cycle.2. Record and report the total regeneration stream...

40 CFR Table 4 to Subpart G of... - Process Vents-Monitoring, Recordkeeping, and Reporting Requirements For Maintaining a TRE Index...

Code of Federal Regulations, 2011 CFR

2011-07-01

... NCS or operating permit—PR. Carbon adsorber d Total regeneration stream mass or volumetric flow during carbon bed regeneration cycle(s) [63.114(b)(3)], and 1. Record of total regeneration stream mass or volumetric flow for each carbon bed regeneration cycle.2. Record and report the total regeneration stream...

40 CFR Table 4 to Subpart G of... - Process Vents-Monitoring, Recordkeeping, and Reporting Requirements For Maintaining a TRE Index...

Code of Federal Regulations, 2012 CFR

2012-07-01

... NCS or operating permit—PR. Carbon adsorber d Total regeneration stream mass or volumetric flow during carbon bed regeneration cycle(s) [63.114(b)(3)], and 1. Record of total regeneration stream mass or volumetric flow for each carbon bed regeneration cycle.2. Record and report the total regeneration stream...

40 CFR Table 6 to Subpart Ppp of... - Process Vents From Continuous Unit Operations-Monitoring, Recordkeeping, and Reporting Requirements

Code of Federal Regulations, 2012 CFR

2012-07-01

... temperature established in the NCS or operating—PR. d,e Carbon Adsorber f Total regeneration stream mass or volumetric flow during carbon bed regeneration cycle(s), and 1. Record of total regeneration stream mass or volumetric flow for each carbon bed regeneration cycle.2. Record and report the total regeneration stream...

40 CFR Table 6 to Subpart Ppp of... - Process Vents From Continuous Unit Operations-Monitoring, Recordkeeping, and Reporting Requirements

Code of Federal Regulations, 2013 CFR

2013-07-01

... operating—PR. d,e Carbon Adsorber f Total regeneration stream mass or volumetric flow during carbon bed regeneration cycle(s), and 1. Record of total regeneration stream mass or volumetric flow for each carbon bed regeneration cycle.2. Record and report the total regeneration stream mass or volumetric flow during each...

40 CFR Table 7 to Subpart G of... - Transfer Operations-Monitoring, Recordkeeping, and Reporting Requirements for Complying With 98...

Code of Federal Regulations, 2010 CFR

2010-07-01

... collected f—PR. Carbon adsorber h Total regeneration stream mass or volumetric or volumetric flow during carbon bed regeneration cycle(s) [63.127(b)(3)], and 1. Record of total regeneration stream mass or volumetric flow for each carbon bed regeneration cycle.2. Record and report the total regeneration stream...

Long cycle life microporous spherical carbon anodes for sodium-ion batteries derived from furfuryl alcohol

DOE PAGES

Zhou, Dehua; Peer, Maryam; Yang, Zhenzhen; ...

2016-04-11

Spherical micron-sized carbon powders were synthesized from feedstock furfuryl alcohol and tested as anodes in sodium ion batteries (SIBs). A long cycle life of 1000 cycles is achievable with this carbon at C rate (3–4 mg cm –2 loading and i = 200 mA g –1) yielding a steady capacity of ca. 115 mA h g –1. Furthermore, the results from solid-state 23Na MAS NMR analyses of cycled electrodes indicate no correlation in voltage profiles with sodium site nature (graphene or nanopores), which is a new observation in SIB carbon anodes.

Effects of Nutrient Enrichment on Microbial Communities and Carbon Cycling in Wetland Soils

NASA Astrophysics Data System (ADS)

Hartman, W.; Neubauer, S. C.; Richardson, C. J.

2013-12-01

Soil microbial communities are responsible for catalyzing biogeochemical transformations underlying critical wetland functions, including cycling of carbon (C) and nutrients, and emissions of greenhouse gasses (GHG). Alteration of nutrient availability in wetland soils may commonly occur as the result of anthropogenic impacts including runoff from human land uses in uplands, alteration of hydrology, and atmospheric deposition. However, the impacts of altered nutrient availability on microbial communities and carbon cycling in wetland soils are poorly understood. To assess these impacts, soil microbial communities and carbon cycling were determined in replicate experimental nutrient addition plots (control, +N, +P, +NP) across several wetland types, including pocosin peat bogs (NC), freshwater tidal marshes (GA), and tidal salt marshes (SC). Microbial communities were determined by pyrosequencing (Roche 454) extracted soil DNA, targeting both bacteria (16S rDNA) and fungi (LSU) at a depth of ca. 1000 sequences per plot. Wetland carbon cycling was evaluated using static chambers to determine soil GHG fluxes, and plant inclusion chambers were used to determine ecosystem C cycling. Soil bacterial communities responded to nutrient addition treatments in freshwater and tidal marshes, while fungal communities did not respond to treatments in any of our sites. We also compared microbial communities to continuous biogeochemical variables in soil, and found that bacterial community composition was correlated only with the content and availability of soil phosphorus, while fungi responded to phosphorus stoichiometry and soil pH. Surprisingly, we did not find a significant effect of our nutrient addition treatments on most metrics of carbon cycling. However, we did find that several metrics of soil carbon cycling appeared much more related to soil phosphorus than to nitrogen or soil carbon pools. Finally, while overall microbial community composition was weakly correlated with soil carbon cycling, our work did identify a small number of individual taxonomic groups that were more strongly correlated with soil CO2 flux. These results suggest that a small number of microbial groups may potentially serve as keystone taxa (and functional indicators), which simple community fingerprinting approaches may overlook. Our results also demonstrate strong effects of soil phosphorus availability on both microbial communities and soil carbon cycling, even in wetland types traditionally considered to be nitrogen limited.

40 CFR Table 4 to Subpart Ggg of... - Monitoring Requirements for Control Devices a

Code of Federal Regulations, 2014 CFR

2014-07-01

... (regenerative) Stream flow monitoring device, and 1. Total regeneration stream mass or volumetric flow during carbon bed regeneration cycle(s) 1. For each regeneration cycle, record the total regeneration stream... regeneration 2. For each regeneration cycle, record the maximum carbon bed-temperature. 3. Temperature of...

40 CFR Table 4 to Subpart Ggg of... - Monitoring Requirements for Control Devices a

Code of Federal Regulations, 2013 CFR

2013-07-01

... (regenerative) Stream flow monitoring device, and 1. Total regeneration stream mass or volumetric flow during carbon bed regeneration cycle(s) 1. For each regeneration cycle, record the total regeneration stream... regeneration 2. For each regeneration cycle, record the maximum carbon bed-temperature. 3. Temperature of...

Carbon-carbon primary structure for SSTO vehicles

NASA Astrophysics Data System (ADS)

Croop, Harold C.; Lowndes, Holland B.

1997-01-01

A hot structures development program is nearing completion to validate use of carbon-carbon composite structure for primary load carrying members in a single-stage-to-orbit, or SSTO, vehicle. A four phase program was pursued which involved design development and fabrication of a full-scale wing torque box demonstration component. The design development included vehicle and component selection, design criteria and approach, design data development, demonstration component design and analysis, test fixture design and analysis, demonstration component test planning, and high temperature test instrumentation development. The fabrication effort encompassed fabrication of structural elements for mechanical property verification as well as fabrication of the demonstration component itself and associated test fixturing. The demonstration component features 3D woven graphite preforms, integral spars, oxidation inhibited matrix, chemical vapor deposited (CVD) SiC oxidation protection coating, and ceramic matrix composite fasteners. The demonstration component has been delivered to the United States Air Force (USAF) for testing in the Wright Laboratory Structural Test Facility, WPAFB, OH. Multiple thermal-mechanical load cycles will be applied simulating two atmospheric cruise missions and one orbital mission. This paper discusses the overall approach to validation testing of the wing box component and presents some preliminary analytical test predictions.

Earth system model simulations show different feedback strengths of the terrestrial carbon cycle under glacial and interglacial conditions

NASA Astrophysics Data System (ADS)

Adloff, Markus; Reick, Christian H.; Claussen, Martin

2018-04-01

In simulations with the MPI Earth System Model, we study the feedback between the terrestrial carbon cycle and atmospheric CO2 concentrations under ice age and interglacial conditions. We find different sensitivities of terrestrial carbon storage to rising CO2 concentrations in the two settings. This result is obtained by comparing the transient response of the terrestrial carbon cycle to a fast and strong atmospheric CO2 concentration increase (roughly 900 ppm) in Coupled Climate Carbon Cycle Model Intercomparison Project (C4MIP)-type simulations starting from climates representing the Last Glacial Maximum (LGM) and pre-industrial times (PI). In this set-up we disentangle terrestrial contributions to the feedback from the carbon-concentration effect, acting biogeochemically via enhanced photosynthetic productivity when CO2 concentrations increase, and the carbon-climate effect, which affects the carbon cycle via greenhouse warming. We find that the carbon-concentration effect is larger under LGM than PI conditions because photosynthetic productivity is more sensitive when starting from the lower, glacial CO2 concentration and CO2 fertilization saturates later. This leads to a larger productivity increase in the LGM experiment. Concerning the carbon-climate effect, it is the PI experiment in which land carbon responds more sensitively to the warming under rising CO2 because at the already initially higher temperatures, tropical plant productivity deteriorates more strongly and extratropical carbon is respired more effectively. Consequently, land carbon losses increase faster in the PI than in the LGM case. Separating the carbon-climate and carbon-concentration effects, we find that they are almost additive for our model set-up; i.e. their synergy is small in the global sum of carbon changes. Together, the two effects result in an overall strength of the terrestrial carbon cycle feedback that is almost twice as large in the LGM experiment as in the PI experiment. For PI, ocean and land contributions to the total feedback are of similar size, while in the LGM case the terrestrial feedback is dominant.

Isotopic inferences of ancient biochemistries - Carbon, sulfur, hydrogen, and nitrogen

NASA Technical Reports Server (NTRS)

Schidlowski, M.; Hayes, J. M.; Kaplan, I. R.

1983-01-01

In processes of biological incorporation and subsequent biochemical processing sizable isotope effects occur as a result of both thermodynamic and kinetic fractionations which take place during metabolic and biosynthetic reactions. In this chapter a review is provided of earlier work and recent studies on isotope fractionations in the biogeochemical cycles of carbon, sulfur, hydrogen, and nitrogen. Attention is given to the biochemistry of carbon isotope fractionation, carbon isotope fractionation in extant plants and microorganisms, isotope fractionation in the terrestrial carbon cycle, the effects of diagenesis and metamorphism on the isotopic composition of sedimentary carbon, the isotopic composition of sedimentary carbon through time, implications of the sedimentary carbon isotope record, the biochemistry of sulfur isotope fractionation, pathways of the biogeochemical cycle of nitrogen, and the D/H ratio in naturally occurring materials.

Carbon sequestration and its role in the global carbon cycle

USGS Publications Warehouse

McPherson, Brian J.; Sundquist, Eric T.

2009-01-01

For carbon sequestration the issues of monitoring, risk assessment, and verification of carbon content and storage efficacy are perhaps the most uncertain. Yet these issues are also the most critical challenges facing the broader context of carbon sequestration as a means for addressing climate change. In response to these challenges, Carbon Sequestration and Its Role in the Global Carbon Cycle presents current perspectives and research that combine five major areas: • The global carbon cycle and verification and assessment of global carbon sources and sinks • Potential capacity and temporal/spatial scales of terrestrial, oceanic, and geologic carbon storage • Assessing risks and benefits associated with terrestrial, oceanic, and geologic carbon storage • Predicting, monitoring, and verifying effectiveness of different forms of carbon storage • Suggested new CO2 sequestration research and management paradigms for the future. The volume is based on a Chapman Conference and will appeal to the rapidly growing group of scientists and engineers examining methods for deliberate carbon sequestration through storage in plants, soils, the oceans, and geological repositories.

Estimating ecosystem carbon change in the Conterminous United States based on 40 years of land-use change and disturbance

NASA Astrophysics Data System (ADS)

Sleeter, B. M.; Rayfield, B.; Liu, J.; Sherba, J.; Daniel, C.; Frid, L.; Wilson, T. S.; Zhu, Z.

2016-12-01

Since 1970, the combined changes in land use, land management, climate, and natural disturbances have dramatically altered land cover in the United States, resulting in the potential for significant changes in terrestrial carbon storage and flux between ecosystems and the atmosphere. Processes including urbanization, agricultural expansion and contraction, and forest management have had impacts - both positive and negative - on the amount of natural vegetation, the age structure of forests, and the amount of impervious cover. Anthropogenic change coupled with climate-driven changes in natural disturbance regimes, particularly the frequency and severity of wildfire, together determine the spatio-temporal patterns of land change and contribute to changing ecosystem carbon dynamics. Quantifying this effect and its associated uncertainties is fundamental to developing a rigorous and transparent carbon monitoring and assessment programs. However, large-scale systematic inventories of historical land change and their associated uncertainties are sparse. To address this need, we present a newly developed modeling framework, the Land Use and Carbon Scenario Simulator (LUCAS). The LUCAS model integrates readily available high quality, empirical land-change data into a stochastic space-time simulation model representing land change feedbacks on carbon cycling in terrestrial ecosystems. We applied the LUCAS model to estimate regional scale changes in carbon storage, atmospheric flux, and net biome production in 84 ecological regions of the conterminous United States for the period 1970-2015. The model was parameterized using a newly available set of high resolution (30 m) land-change data, compiled from Landsat remote sensing imagery, including estimates of uncertainty. Carbon flux parameters for each ecological region were derived from the IBIS dynamic global vegetation model with full carbon cycle accounting. This paper presents our initial findings describing regional and temporal changes and variability in carbon storage and flux resulting from land use change and disturbance between 1973 and 2015. Additionally, based on stochastic simulations we quantify and present key sources of uncertainty in the estimation of terrestrial ecosystem carbon dynamics.

The NOAA Carbon America Program A Focus on Products for Decision- Support

NASA Astrophysics Data System (ADS)

Butler, J. H.; Hofmann, D. J.; Tans, P. P.; Peters, W.; Andrews, A. E.; Sweeny, C.; Montzka, S. A.

2006-12-01

If society is to manage or reduce carbon emissions in the future, reliable and accurate information on atmospheric carbon dioxide levels for verification of emission reductions will be needed on local, regional, and global scales. The current global carbon dioxide observing network operated by NOAA/ESRL provides a foundation for monitoring and understanding carbon dioxide. For example, atmospheric measurements in Europe suggest that emissions inventories of methane are substantial underestimates. An expanded U.S. Carbon Cycle Atmospheric Observing System is being implemented. Carbon America will consist of approximately 24 aircraft and 12 tall towers obtaining concentrations of carbon gases and other trace species. This observing system needs to be capable of quantitative attribution of all major contributors to the carbon budget of the continent, both manmade and natural. Successful mitigation strategies need independent and credible assessments of their efficacy. Managing carbon emissions will require the involvement of industry, financial markets, and governments at all levels. Without good information, governments will be slow to act, private investments will likely be less than optimal, and financial markets will not develop as they might need to. The atmospheric data and the methods used to derive sources and sinks will be fully open and available in up-to-date form to scientists, the general public, and policymakers. This presentation will provide an overview of NOAA`s role in the North American Carbon Program, our current accomplishments, our plans for the future network, and the currently expected products, services, and information that derive from these and other associated studies. Today's products, while useful, will be eclipsed by those of tomorrow, which will focus heavily on regional emissions expressed on seasonal or shorter time-scales, and will provide needed information for improved predictions in the future.

Quantifying carbon footprint reduction opportunities for U.S. households and communities.

PubMed

Jones, Christopher M; Kammen, Daniel M

2011-05-01

Carbon management is of increasing interest to individuals, households, and communities. In order to effectively assess and manage their climate impacts, individuals need information on the financial and greenhouse gas benefits of effective mitigation opportunities. We use consumption-based life cycle accounting techniques to quantify the carbon footprints of typical U.S. households in 28 cities for 6 household sizes and 12 income brackets. The model includes emissions embodied in transportation, energy, water, waste, food, goods, and services. We further quantify greenhouse gas and financial savings from 13 potential mitigation actions across all household types. The model suggests that the size and composition of carbon footprints vary dramatically between geographic regions and within regions based on basic demographic characteristics. Despite these differences, large cash-positive carbon footprint reductions are evident across all household types and locations; however, realizing this potential may require tailoring policies and programs to different population segments with very different carbon footprint profiles. The results of this model have been incorporated into an open access online carbon footprint management tool designed to enable behavior change at the household level through personalized feedback.

Tunneled Mesoporous Carbon Nanofibers with Embedded ZnO Nanoparticles for Ultrafast Lithium Storage.

PubMed

An, Geon-Hyoung; Lee, Do-Young; Ahn, Hyo-Jin

2017-04-12

Carbon and metal oxide composites have received considerable attention as anode materials for Li-ion batteries (LIBs) owing to their excellent cycling stability and high specific capacity based on the chemical and physical stability of carbon and the high theoretical specific capacity of metal oxides. However, efforts to obtain ultrafast cycling stability in carbon and metal oxide composites at high current density for practical applications still face important challenges because of the longer Li-ion diffusion pathway, which leads to poor ultrafast performance during cycling. Here, tunneled mesoporous carbon nanofibers with embedded ZnO nanoparticles (TMCNF/ZnO) are synthesized by electrospinning, carbonization, and postcalcination. The optimized TMCNF/ZnO shows improved electrochemical performance, delivering outstanding ultrafast cycling stability, indicating a higher specific capacity than previously reported ZnO-based anode materials in LIBs. Therefore, the unique architecture of TMCNF/ZnO has potential for use as an anode material in ultrafast LIBs.

An Assessment of the Potential Effects of Aquifer Storage and Recovery on Mercury Cycling in South Florida

USGS Publications Warehouse

Krabbenhoft, David P.; Aiken, George R.; Anderson, Mary P.

2007-01-01

Mercury contamination in the environment is a global concern, especially in areas with abundant wetlands, such as south Florida. As the causal factors of this concern improve, scientists find that many factors that do not necessarily affect mercury concentrations, such as flooding and drying cycles, or changes to carbon and sulfate loading, can profoundly affect net mercury toxicity. Especially important are ecological factors that alter the conversion of mercury to methylmercury, which is the most bioaccumulative and toxic form of mercury in the environment. Resource managers, therefore, need to be aware of possible deleterious affects to mercury toxicity that could result from land and water management decisions. Several aspects of the Comprehensive Everglades Restoration Plan (CERP), including the planned Aquifer Storage and Recovery (ASR) program, have the potential to affect the abundance of methylmercury. In response to these concerns, the U.S. Geological Survey and U.S. Army Corps of Engineers collaborated on a study to evaluate how the proposed ASR program may affect mercury cycling and toxicity. This project was conducted as an initial assessment of the possible effects of the CERP ASR program on mercury in the south Florida environment. A twofold approach was employed: field sampling and controlled laboratory benchmark experiments. The field sampling survey collected ground-water samples from the Floridan and surficial aquifer systems for the ASR program to determine existing levels of mercury and methylmercury. Laboratory experiments, on the other hand, were designed to determine how the injected surface water would interact with the aquifer during storage periods. Overall, very low levels of mercury and methylmercury (mean values of 0.41 and 0.07 nanograms per liter, respectively) were observed in ground-water samples collected from the Floridan and surficial aquifer systems. These results indicate that 'recovered water' from the CERP ASR program would not represent a significant additional direct load of mercury and methyl-mercury to ASR 'receiving waters'. Net production of methylmercury, however, can result from additions of sulfate or natural organic carbon. Thus, because the Upper Floridan aquifer generally has elevated concentrations of sulfate (relative to ambient Everglades conditions) and surface waters near Lake Okeechobee (the assumed target for ASR receiving waters) are elevated in organic carbon and sulfate, at least some potential for increased methylmercury production might arise from the release of recovered ASR water to locations in or near the Everglades.

ARM Carbon Cycle Gases Flasks at SGP Site

DOE Data Explorer

Biraud, Sebastien

2013-03-26

Data from flasks are sampled at the Atmospheric Radiation Measurement Program ARM, Southern Great Plains Site and analyzed by the National Oceanic and Atmospheric Administration NOAA, Earth System Research Laboratory ESRL. The SGP site is included in the NOAA Cooperative Global Air Sampling Network. The surface samples are collected from a 60 m tower at the ARM SGP Central Facility, usually once per week in the afternoon. The aircraft samples are collected approximately weekly from a chartered aircraft, and the collection flight path is centered over the tower where the surface samples are collected. The samples are collected by the ARM and LBNL Carbon Project.

The Yeast Cyclin-Dependent Kinase Routes Carbon Fluxes to Fuel Cell Cycle Progression.

PubMed

Ewald, Jennifer C; Kuehne, Andreas; Zamboni, Nicola; Skotheim, Jan M

2016-05-19

Cell division entails a sequence of processes whose specific demands for biosynthetic precursors and energy place dynamic requirements on metabolism. However, little is known about how metabolic fluxes are coordinated with the cell division cycle. Here, we examine budding yeast to show that more than half of all measured metabolites change significantly through the cell division cycle. Cell cycle-dependent changes in central carbon metabolism are controlled by the cyclin-dependent kinase (Cdk1), a major cell cycle regulator, and the metabolic regulator protein kinase A. At the G1/S transition, Cdk1 phosphorylates and activates the enzyme Nth1, which funnels the storage carbohydrate trehalose into central carbon metabolism. Trehalose utilization fuels anabolic processes required to reliably complete cell division. Thus, the cell cycle entrains carbon metabolism to fuel biosynthesis. Because the oscillation of Cdk activity is a conserved feature of the eukaryotic cell cycle, we anticipate its frequent use in dynamically regulating metabolism for efficient proliferation. Copyright © 2016 Elsevier Inc. All rights reserved.

1D Ni-Co oxide and sulfide nanoarray/carbon aerogel hybrid nanostructures for asymmetric supercapacitors with high energy density and excellent cycling stability.

PubMed

Hao, Pin; Tian, Jian; Sang, Yuanhua; Tuan, Chia-Chi; Cui, Guanwei; Shi, Xifeng; Wong, C P; Tang, Bo; Liu, Hong

2016-09-15

The fabrication of supercapacitor electrodes with high energy density and excellent cycling stability is still a great challenge. A carbon aerogel, possessing a hierarchical porous structure, high specific surface area and electrical conductivity, is an ideal backbone to support transition metal oxides and bring hope to prepare electrodes with high energy density and excellent cycling stability. Therefore, NiCo 2 S 4 nanotube array/carbon aerogel and NiCo 2 O 4 nanoneedle array/carbon aerogel hybrid supercapacitor electrode materials were synthesized by assembling Ni-Co precursor needle arrays on the surface of the channel walls of hierarchical porous carbon aerogels derived from chitosan in this study. The 1D nanostructures grow on the channel surface of the carbon aerogel vertically and tightly, contributing to the enhanced electrochemical performance with ultrahigh energy density. The energy density of NiCo 2 S 4 nanotube array/carbon aerogel and NiCo 2 O 4 nanoneedle array/carbon aerogel hybrid asymmetric supercapacitors can reach up to 55.3 Wh kg -1 and 47.5 Wh kg -1 at a power density of 400 W kg -1 , respectively. These asymmetric devices also displayed excellent cycling stability with a capacitance retention of about 96.6% and 92% over 5000 cycles.

Moving Carbon, Changing Earth: Bringing the Carbon Cycle to Life

NASA Astrophysics Data System (ADS)

Zabel, I.; Duggan-Haas, D.; Ross, R. M.; Stricker, B.; Mahowald, N. M.

2014-12-01

The carbon cycle presents challenges to researchers - in how to understand the complex interactions of fluxes, reservoirs, and systems - and to outreach professionals - in how to get across the complexity of the carbon cycle and still make it accessible to the public. At Cornell University and the Museum of the Earth in Ithaca, NY, researchers and outreach staff tackled these challenges together through a 2013 temporary museum exhibition: Moving Carbon, Changing Earth. Moving Carbon, Changing Earth introduced visitors to the world of carbon and its effect on every part of our lives. The exhibit was the result of the broader impacts portion of an NSF grant awarded to Natalie Mahowald, Professor in the Department of Earth and Atmospheric Sciences at Cornell University, who has been working with a team to improve simulations of regional and decadal variability in the carbon cycle. Within the exhibition, visitors used systems thinking to understand the distribution of carbon in and among Earth's systems, learning how (and how quickly or slowly) carbon moves between and within these systems, the relative scale of different reservoirs, and how carbon's movement changes climate and other environmental dynamics. Five interactive stations represented the oceans, lithosphere, atmosphere, biosphere, and a mystery reservoir. Puzzles, videos, real specimens, and an interview with Mahowald clarified and communicated the complexities of the carbon cycle. In this talk we'll present background information on Mahowald's research as well as photos of the exhibition and discussion of the components and motivations behind them, showing examples of innovative ways to bring a complex topic to life for museum visitors.

Recent trends, drivers, and projections of carbon cycle processes in forests and grasslands of North America

NASA Astrophysics Data System (ADS)

Domke, G. M.; Williams, C. A.; Birdsey, R.; Pendall, E.

2017-12-01

In North America forest and grassland ecosystems play a major role in the carbon cycle. Here we present the latest trends and projections of United States and North American carbon cycle processes, stocks, and flows in the context of interactions with global scale budgets and climate change impacts in managed and unmanaged grassland and forest ecosystems. We describe recent trends in natural and anthropogenic disturbances in these ecosystems as well as the carbon dynamics associated with land use and land cover change. We also highlight carbon management science and tools for informing decisions and opportunities for improving carbon measurements, observations, and projections in forests and grasslands.

Estimation of Carbon Sink in Surface Carbonate Rocks of Guangxi Province by Using Remote Sensing Images

NASA Astrophysics Data System (ADS)

Jia, B.; Zhou, G.; Wang, H.; Yue, T.; Huang, W.

2018-04-01

Studies of the imbalance of source sinks in the carbon cycle show that CO2 absorbed during rock weathering is part of the "miss carbon" of the global carbon cycle. The carbon sink contribution of carbonate rocks obviously plays a very important role in the absorption of atmospheric CO2. Estimation of carbon sinks in karst dynamic system of Guangxi province has great significance for further understanding of global karst carbon cycle and global climate research. This paper quotes the rock data from Tao Xiaodong's paper, which is obtained using RS and GIS techniques. At the same time, the dissolution rate model studied by Zhou Guoqing and others was used to estimate the dissolution rate of carbonate rocks in Guangxi Province. Finally, the CO2 content consumed by carbonate karstification in Guangxi Province was 1342910.447 t a-1. The results obtained are in the same order of magnitude as the CO2 content consumed by carbonate rock karstification in Guangxi Province calculated by Tao Xiaodong.

Long-Term, Autonomous Measurement of Atmospheric Carbon Dioxide Using an Ormosil Nanocomposite-Based Optical Sensor

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

Kisholoy Goswami

2005-10-11

The goal of this project is to construct a prototype carbon dioxide sensor that can be commercialized to offer a low-cost, autonomous instrument for long-term, unattended measurements. Currently, a cost-effective CO2 sensor system is not available that can perform cross-platform measurements (ground-based or airborne platforms such as balloon and unmanned aerial vehicle (UAV)) for understanding the carbon sequestration phenomenon. The CO2 sensor would support the research objectives of DOE-sponsored programs such as AmeriFlux and the North American Carbon Program (NACP). Global energy consumption is projected to rise 60% over the next 20 years and use of oil is projected tomore » increase by approximately 40%. The combustion of coal, oil, and natural gas has increased carbon emissions globally from 1.6 billion tons in 1950 to 6.3 billion tons in 2000. This figure is expected to reach 10 billon tons by 2020. It is important to understand the fate of this excess CO2 in the global carbon cycle. The overall goal of the project is to develop an accurate and reliable optical sensor for monitoring carbon dioxide autonomously at least for one year at a point remote from the actual CO2 release site. In Phase I of this project, InnoSense LLC (ISL) demonstrated the feasibility of an ormosil-monolith based Autonomous Sensor for Atmospheric CO2 (ASAC) device. All of the Phase I objectives were successfully met.« less

Carbon assimilation and transfer through kelp forests in the NE Atlantic is diminished under a warmer ocean climate.

PubMed

Pessarrodona, Albert; Moore, Pippa J; Sayer, Martin D J; Smale, Dan A

2018-06-03

Global climate change is affecting carbon cycling by driving changes in primary productivity and rates of carbon fixation, release and storage within Earth's vegetated systems. There is, however, limited understanding of how carbon flow between donor and recipient habitats will respond to climatic changes. Macroalgal-dominated habitats, such as kelp forests, are gaining recognition as important carbon donors within coastal carbon cycles, yet rates of carbon assimilation and transfer through these habitats are poorly resolved. Here, we investigated the likely impacts of ocean warming on coastal carbon cycling by quantifying rates of carbon assimilation and transfer in Laminaria hyperborea kelp forests-one of the most extensive coastal vegetated habitat types in the NE Atlantic-along a latitudinal temperature gradient. Kelp forests within warm climatic regimes assimilated, on average, more than three times less carbon and donated less than half the amount of particulate carbon compared to those from cold regimes. These patterns were not related to variability in other environmental parameters. Across their wider geographical distribution, plants exhibited reduced sizes toward their warm-water equatorward range edge, further suggesting that carbon flow is reduced under warmer climates. Overall, we estimated that Laminaria hyperborea forests stored ~11.49 Tg C in living biomass and released particulate carbon at a rate of ~5.71 Tg C year -1 . This estimated flow of carbon was markedly higher than reported values for most other marine and terrestrial vegetated habitat types in Europe. Together, our observations suggest that continued warming will diminish the amount of carbon that is assimilated and transported through temperate kelp forests in NE Atlantic, with potential consequences for the coastal carbon cycle. Our findings underline the need to consider climate-driven changes in the capacity of ecosystems to fix and donate carbon when assessing the impacts of climate change on carbon cycling. © 2018 The Authors Global Change Biology Published by John Wiley & Sons Ltd.

40 CFR Table 7 to Subpart Jjj of... - Group 1 Batch Process Vents and Aggregate Batch Vent Streams-Monitoring, Recordkeeping, and...

Code of Federal Regulations, 2012 CFR

2012-07-01

... collected—PR. d,e Carbon Adsorber f a. Total regeneration steam flow or nitrogen flow, or pressure (gauge or absolute) during carbon bed regeneration cycle(s), and 1. Record the total regeneration steam flow or nitrogen flow, or pressure for each carbon bed regeneration cycle.2. Record and report the total...

40 CFR Table 6 to Subpart U of... - Group 1 Batch Front-End Process Vents and Aggregate Batch Vent Streams-Monitoring, Recordkeeping...

Code of Federal Regulations, 2012 CFR

2012-07-01

... collected—PR. d,e Carbon adsorber f a. Total regeneration steam flow or nitrogen flow, or pressure gauge or absolute) during carbon bed regeneration cycle(s), and 1. Record of total regeneration steam flow or nitrogen flow, or pressure for each carbon bed regeneration cycle. 2. Record and report the total...

40 CFR Table 6 to Subpart U of... - Group 1 Batch Front-End Process Vents and Aggregate Batch Vent Streams-Monitoring, Recordkeeping...

Code of Federal Regulations, 2011 CFR

2011-07-01

... collected—PR. d,e Carbon adsorber f a. Total regeneration steam flow or nitrogen flow, or pressure gauge or absolute) during carbon bed regeneration cycle(s), and 1. Record of total regeneration steam flow or nitrogen flow, or pressure for each carbon bed regeneration cycle. 2. Record and report the total...

40 CFR Table 7 to Subpart Jjj of... - Group 1 Batch Process Vents and Aggregate Batch Vent Streams-Monitoring, Recordkeeping, and...

Code of Federal Regulations, 2010 CFR

2010-07-01

... collected—PR. d,e Carbon Adsorber f a. Total regeneration steam flow or nitrogen flow, or pressure (gauge or absolute) during carbon bed regeneration cycle(s), and 1. Record the total regeneration steam flow or nitrogen flow, or pressure for each carbon bed regeneration cycle.2. Record and report the total...

40 CFR Table 6 to Subpart U of... - Group 1 Batch Front-End Process Vents and Aggregate Batch Vent Streams-Monitoring, Recordkeeping...

Code of Federal Regulations, 2013 CFR

2013-07-01

... collected—PR. d,e Carbon adsorber f a. Total regeneration steam flow or nitrogen flow, or pressure gauge or absolute) during carbon bed regeneration cycle(s), and 1. Record of total regeneration steam flow or nitrogen flow, or pressure for each carbon bed regeneration cycle. 2. Record and report the total...

40 CFR Table 6 to Subpart U of... - Group 1 Batch Front-End Process Vents and Aggregate Batch Vent Streams-Monitoring, Recordkeeping...

Code of Federal Regulations, 2010 CFR

2010-07-01

... collected—PR. d,e Carbon adsorber f a. Total regeneration steam flow or nitrogen flow, or pressure gauge or absolute) during carbon bed regeneration cycle(s), and 1. Record of total regeneration steam flow or nitrogen flow, or pressure for each carbon bed regeneration cycle. 2. Record and report the total...

40 CFR Table 7 to Subpart Jjj of... - Group 1 Batch Process Vents and Aggregate Batch Vent Streams-Monitoring, Recordkeeping, and...

Code of Federal Regulations, 2013 CFR

2013-07-01

... collected—PR. d,e Carbon Adsorber f a. Total regeneration steam flow or nitrogen flow, or pressure (gauge or absolute) during carbon bed regeneration cycle(s), and 1. Record the total regeneration steam flow or nitrogen flow, or pressure for each carbon bed regeneration cycle.2. Record and report the total...

40 CFR Table 7 to Subpart Jjj of... - Group 1 Batch Process Vents and Aggregate Batch Vent Streams-Monitoring, Recordkeeping, and...

Code of Federal Regulations, 2011 CFR

2011-07-01

... collected—PR. d,e Carbon Adsorber f a. Total regeneration steam flow or nitrogen flow, or pressure (gauge or absolute) during carbon bed regeneration cycle(s), and 1. Record the total regeneration steam flow or nitrogen flow, or pressure for each carbon bed regeneration cycle.2. Record and report the total...

40 CFR Table 6 to Subpart U of... - Group 1 Batch Front-End Process Vents and Aggregate Batch Vent Streams-Monitoring, Recordkeeping...

Code of Federal Regulations, 2014 CFR

2014-07-01

... collected—PR. d e Carbon adsorber f a. Total regeneration steam flow or nitrogen flow, or pressure gauge or absolute) during carbon bed regeneration cycle(s), and 1. Record of total regeneration steam flow or nitrogen flow, or pressure for each carbon bed regeneration cycle. 2. Record and report the total...

40 CFR Table 7 to Subpart Jjj of... - Group 1 Batch Process Vents and Aggregate Batch Vent Streams-Monitoring, Recordkeeping, and...

Code of Federal Regulations, 2014 CFR

2014-07-01

... collected—PR. d e Carbon Adsorber f a. Total regeneration steam flow or nitrogen flow, or pressure (gauge or absolute) during carbon bed regeneration cycle(s), and 1. Record the total regeneration steam flow or nitrogen flow, or pressure for each carbon bed regeneration cycle.2. Record and report the total...

No One's Home: the Fate of Carbon on Lifeless Earths

NASA Astrophysics Data System (ADS)

Neveu, Marc

Although several thousands of exoplanets are now known, including many terrestrial planets, their possible geology and climates remain poorly understood and understudied. Yet, understanding how elements such as carbon are cycled between a planet's interior, surface, and atmosphere is crucial to predict how lifeless planets operate and, by contrast, be able to detect deviations from abiotic backgrounds due to biology, the holy grail of exoplanet science. As a first, feasible step towards the difficult, long-term goal of understanding how key reactive elements (H, C, N, O, S) are cycled in the atmospheres, surfaces, and interiors of terrestrial exoplanets through time, we propose to carry out a self-consistent theoretical study of the fate of carbon in the atmospheres and at the surfaces of Earth-like, lifeless exoplanets. We will: 1. Model the near-surface geochemistry and geophysics of the carbon cycle to determine net carbon gas fluxes as a function of terrestrial planet size and redox conditions; 2. Model the atmospheric fate of carbon species as a function of stellar input; 3. Perform simulations that self-consistently combine geological and atmospheric processes; 4. Convert resulting atmospheric compositions to spectra to be archived as a public database for use by observers. We will track the abiotic fate of carbon and its atmospheric expression on Earth-like planets as a function of three key parameters: planet size, surface and atmospheric redox conditions, and stellar irradiation. To do so, we will further develop and use state-of-theart planetary geological ("Geo") and atmospheric ("Atmos") models. We have previously developed a code that couples geophysical evolution and water-rock geochemistry (Neveu et al. 2015, GRL 42, 10197). Using this code, we will calculate the speciation of carbon species versus depth in subaerial oceans, their possible incorporation into the crust by water-rock interaction at the seafloor or by subduction of sediments, and outgassing as a function of temperature, pressure, and fluid/rock composition. We will expand this code with benchmarked parameterizations of land and seafloor weathering and outgassing rates. This modeling will result in detailed boundary conditions to be implemented into an existing atmospheric photochemical-climate model (DomagalGoldman et al. 2014, ApJ 792, 90). The atmospheric model will be used to predict species mixing ratios from net surface fluxes, given planetary and stellar parameters. The models will be benchmarked against what is known of the surfaces and atmospheres of the Earth (present and prior to atmospheric oxygenation) and Titan. Atmospheric model outputs will be fed back into the geological model in combined simulations of carbon cycling. We will investigate in detail the mutual feedbacks between geological and atmospheric processes, so far understudied for terrestrial exoplanets. The resulting atmospheric compositions will be converted to predicted exoplanet spectra using the Spectral Mapping Atmospheric Radiative Transfer model (SMART; Meadows & Crisp 1996, JGR 101, 4595). This grid of spectra will be made freely available to the exoplanet community. This proposal is relevant to the Exoplanets Research Program (E.3) objectives, as it "supports directly the scientific goals of advancing our knowledge and understanding of exoplanetary systems." It involves the "characterization of exoplanets (including their surfaces, interiors, and atmospheres) [...] including the determination of their compositions, dynamics, energetics, and chemical behaviors." This investigation will also advance "understanding the chemical and physical processes of exoplanets (including the state and evolution of their surfaces, interiors, and atmospheres)." Furthermore, this proposal is not "aimed at investigating the habitability of an exoplanet" and therefore not relevant to the Habitable Worlds program element (E.4).

The History and Impact of the CNO Cycles in Nuclear Astrophysics

NASA Astrophysics Data System (ADS)

Wiescher, Michael

2018-03-01

The carbon cycle, or Bethe-Weizsäcker cycle, plays an important role in astrophysics as one of the most important energy sources for quiescent and explosive hydrogen burning in stars. This paper presents the intellectual and historical background of the idea of the correlation between stellar energy production and the synthesis of the chemical elements in stars on the example of this cycle. In particular, it addresses the contributions of Carl Friedrich von Weizsäcker and Hans Bethe, who provided the first predictions of the carbon cycle. Further, the experimental verification of the predicted process as it developed over the following decades is discussed, as well as the extension of the initial carbon cycle to the carbon-nitrogen-oxygen (CNO) multi-cycles and the hot CNO cycles. This development emerged from the detailed experimental studies of the associated nuclear reactions over more than seven decades. Finally, the impact of the experimental and theoretical results on our present understanding of hydrogen burning in different stellar environments is presented, as well as the impact on our understanding of the chemical evolution of our universe.

Scenarios for low carbon and low water electric power plant ...

EPA Pesticide Factsheets

In the water-energy nexus, water use for the electric power sector is critical. Currently, the operational phase of electric power production dominates the electric sector's life cycle withdrawal and consumption of fresh water resources. Water use associated with the fuel cycle and power plant equipment manufacturing phase is substantially lower on a life cycle basis. An outstanding question is: how do regional shifts to lower carbon electric power mixes affect the relative contribution of the upstream life cycle water use? To test this, we examine a range of scenarios comparing a baseline with scenarios of carbon reduction and water use constraints using the MARKet ALlocation (MARKAL) energy systems model with ORD's 2014 U.S. 9-region database (EPAUS9r). The results suggest that moving toward a low carbon and low water electric power mix may increase the non-operational water use. In particular, power plant manufacturing water use for concentrating solar power, and fuel cycle water use for biomass feedstock, could see sharp increases under scenarios of high deployment of these low carbon options. Our analysis addresses the following questions. First, how does moving to a lower carbon electricity generation mix affect the overall regional electric power water use from a life cycle perspective? Second, how does constraining the operational water use for power plants affect the mix, if at all? Third, how does the life cycle water use differ among regions under

Improved Ionic Diffusion through the Mesoporous Carbon Skin on Silicon Nanoparticles Embedded in Carbon for Ultrafast Lithium Storage.

PubMed

An, Geon-Hyoung; Kim, Hyeonjin; Ahn, Hyo-Jin

2018-02-21

Because of their combined effects of outstanding mechanical stability, high electrical conductivity, and high theoretical capacity, silicon (Si) nanoparticles embedded in carbon are a promising candidate as electrode material for practical utilization in Li-ion batteries (LIBs) to replace the conventional graphite. However, because of the poor ionic diffusion of electrode materials, the low-grade ultrafast cycling performance at high current densities remains a considerable challenge. In the present study, seeking to improve the ionic diffusion, we propose a novel design of mesoporous carbon skin on the Si nanoparticles embedded in carbon by hydrothermal reaction, poly(methyl methacrylate) coating process, and carbonization. The resultant electrode offers a high specific discharge capacity with excellent cycling stability (1140 mA h g -1 at 100 mA g -1 after 100 cycles), superb high-rate performance (969 mA h g -1 at 2000 mA g -1 ), and outstanding ultrafast cycling stability (532 mA h g -1 at 2000 mA g -1 after 500 cycles). The battery performances are surpassing the previously reported results for carbon and Si composite-based electrodes on LIBs. Therefore, this novel approach provides multiple benefits in terms of the effective accommodation of large volume expansions of the Si nanoparticles, a shorter Li-ion diffusion pathway, and stable electrochemical conditions from a faster ionic diffusion during cycling.

Hard-Soft Composite Carbon as a Long-Cycling and High-Rate Anode for Potassium-Ion Batteries

DOE PAGES

Jian, Zelang; Hwang, Sooyeon; Li, Zhifei; ...

2017-05-05

There exist tremendous needs for sustainable storage solutions for intermittent renewable energy sources, such as solar and wind energy. Thus, systems based on Earth-abundant elements deserve much attention. Potassium-ion batteries represent a promising candidate because of the abundance of potassium resources. As for the choices of anodes, graphite exhibits encouraging potassium-ion storage properties; however, it suffers limited rate capability and poor cycling stability. Here in this paper, nongraphitic carbons as K-ion anodes with sodium carboxymethyl cellulose as the binder are systematically investigated. Compared to hard carbon and soft carbon, a hard–soft composite carbon with 20 wt% soft carbon distributed inmore » the matrix phase of hard carbon microspheres exhibits highly amenable performance: high capacity, high rate capability, and very stable long-term cycling. In contrast, pure hard carbon suffers limited rate capability, while the capacity of pure soft carbon fades more rapidly.« less

Hard-Soft Composite Carbon as a Long-Cycling and High-Rate Anode for Potassium-Ion Batteries

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

Jian, Zelang; Hwang, Sooyeon; Li, Zhifei

There exist tremendous needs for sustainable storage solutions for intermittent renewable energy sources, such as solar and wind energy. Thus, systems based on Earth-abundant elements deserve much attention. Potassium-ion batteries represent a promising candidate because of the abundance of potassium resources. As for the choices of anodes, graphite exhibits encouraging potassium-ion storage properties; however, it suffers limited rate capability and poor cycling stability. Here in this paper, nongraphitic carbons as K-ion anodes with sodium carboxymethyl cellulose as the binder are systematically investigated. Compared to hard carbon and soft carbon, a hard–soft composite carbon with 20 wt% soft carbon distributed inmore » the matrix phase of hard carbon microspheres exhibits highly amenable performance: high capacity, high rate capability, and very stable long-term cycling. In contrast, pure hard carbon suffers limited rate capability, while the capacity of pure soft carbon fades more rapidly.« less

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.

Global covariation of carbon turnover times with climate in terrestrial ecosystems.

PubMed

Carvalhais, Nuno; Forkel, Matthias; Khomik, Myroslava; Bellarby, Jessica; Jung, Martin; Migliavacca, Mirco; Mu, Mingquan; Saatchi, Sassan; Santoro, Maurizio; Thurner, Martin; Weber, Ulrich; Ahrens, Bernhard; Beer, Christian; Cescatti, Alessandro; Randerson, James T; Reichstein, Markus

2014-10-09

The response of the terrestrial carbon cycle to climate change is among the largest uncertainties affecting future climate change projections. The feedback between the terrestrial carbon cycle and climate is partly determined by changes in the turnover time of carbon in land ecosystems, which in turn is an ecosystem property that emerges from the interplay between climate, soil and vegetation type. Here we present a global, spatially explicit and observation-based assessment of whole-ecosystem carbon turnover times that combines new estimates of vegetation and soil organic carbon stocks and fluxes. We find that the overall mean global carbon turnover time is 23(+7)(-4) years (95 per cent confidence interval). On average, carbon resides in the vegetation and soil near the Equator for a shorter time than at latitudes north of 75° north (mean turnover times of 15 and 255 years, respectively). We identify a clear dependence of the turnover time on temperature, as expected from our present understanding of temperature controls on ecosystem dynamics. Surprisingly, our analysis also reveals a similarly strong association between turnover time and precipitation. Moreover, we find that the ecosystem carbon turnover times simulated by state-of-the-art coupled climate/carbon-cycle models vary widely and that numerical simulations, on average, tend to underestimate the global carbon turnover time by 36 per cent. The models show stronger spatial relationships with temperature than do observation-based estimates, but generally do not reproduce the strong relationships with precipitation and predict faster carbon turnover in many semi-arid regions. Our findings suggest that future climate/carbon-cycle feedbacks may depend more strongly on changes in the hydrological cycle than is expected at present and is considered in Earth system models.

Not all droughts are created equal: The impacts of interannual drought pattern and magnitude on grassland carbon cycling

USGS Publications Warehouse

Hoover, David L.; Rogers, Brendan M.

2016-01-01

Climate extremes, such as drought, may have immediate and potentially prolonged effects on carbon cycling. Grasslands store approximately one-third of all terrestrial carbon and may become carbon sources during droughts. However, the magnitude and duration of drought-induced disruptions to the carbon cycle, as well as the mechanisms responsible, remain poorly understood. Over the next century, global climate models predict an increase in two types of drought: chronic but subtle ‘press-droughts’, and shorter term but extreme ‘pulse-droughts’. Much of our current understanding of the ecological impacts of drought comes from experimental rainfall manipulations. These studies have been highly valuable, but are often short term and rarely quantify carbon feedbacks. To address this knowledge gap, we used the Community Land Model 4.0 to examine the individual and interactive effects of pulse- and press-droughts on carbon cycling in a mesic grassland of the US Great Plains. A series of modeling experiments were imposed by varying drought magnitude (precipitation amount) and interannual pattern (press- vs. pulse-droughts) to examine the effects on carbon storage and cycling at annual to century timescales. We present three main findings. First, a single-year pulse-drought had immediate and prolonged effects on carbon storage due to differential sensitivities of ecosystem respiration and gross primary production. Second, short-term pulse-droughts caused greater carbon loss than chronic press-droughts when total precipitation reductions over a 20-year period were equivalent. Third, combining pulse- and press-droughts had intermediate effects on carbon loss compared to the independent drought types, except at high drought levels. Overall, these results suggest that interannual drought pattern may be as important for carbon dynamics as drought magnitude and that extreme droughts may have long-lasting carbon feedbacks in grassland ecosystems.

Modeling 400-500-kyr Pleistocene carbon isotope cyclicity through variations in the dissolved organic carbon pool

NASA Astrophysics Data System (ADS)

Ma, Wentao; Wang, Pinxian; Tian, Jun

2017-05-01

The carbon isotope (δ13C) record from the Plio-Pleistocene shows prominent 400-kyr cycles with maximum values at eccentricity minima during the Pliocene. The period extends to 500 kyr in the Pleistocene after 1.6 Ma. Five δ13C maxima occurred at 0.2, 0.5, 1.0, 1.5 and 1.9 Ma over the last 2 Ma. Although several hypotheses have been suggested to explain why the 400-500-kyr cycles are so strong in δ13C records and how they may have originated, the mechanism is still not clear. The aim of this study was to test the dissolved organic carbon (DOC) hypothesis, which was proposed recently to explain this 400-500-kyr cycle in deeper time. We used an intermediate complexity box model that is computationally efficient for studies involving longer timescales. The model incorporates sophisticated microbial processes, dividing the oceanic carbon cycle into a rapid and a slow cycle. The model result suggests that when more nutrients enter the surface ocean, the rapid carbon cycle is more active, and less refractory DOC (RDOC) is produced. The opposite sequence occurs when fewer nutrients enter the ocean. The modeled RDOC concentration and the δ13C of dissolved inorganic carbon (DIC) are anti-correlated with riverine nutrient input. According to mass conservation, the release of isotopically lighter carbon from the RDOC pool leads to lighter DIC δ13C while an increase in the RDOC pool enriches it. The transient simulations produced a one-to-one correspondence between modeled and measured δ13C. This study supports the hypothesis that chemical weathering-induced variations in the DOC pool act as a pacemaker for δ13C changes over 400-500-kyr cycles.

Sources and sinks of carbon in boreal ecosystems of interior Alaska: a review

USGS Publications Warehouse

Douglas, Thomas A.; Jones, Miriam C.; Hiemstra, Christopher A.

2014-01-01

Boreal regions store large quantities of carbon but are increasingly vulnerable to carbon loss due to disturbance and climate warming. The boreal region, underlain by discontinuous permafrost, presents a challenging landscape for itemizing current and potential carbon sources and sinks in the boreal soil and vegetation. The roles of fire, forest succession, and the presence (or absence) of permafrost on carbon cycle, vegetation, and hydrologic processes have been the focus of multidisciplinary research in this area for the past 20 years. However, projections of a warming future climate, an increase in fire severity and extent, and the potential degradation of permafrost could lead to major landscape process changes over the next 20 to 50 years. This provides a major challenge for predicting how the interplay between land management activities and impacts of climate warming will affect carbon sources and sinks in Interior Alaska. To assist land managers in adapting and managing for potential changes in the Interior Alaska carbon cycle we developed this review paper incorporating an overview of the climate, ecosystem processes, vegetation types, and soil regimes in Interior Alaska with a focus on ramifications for the carbon cycle. Our objective is to provide a synthesis of the most current carbon storage estimates and measurements to support policy and land management decisions on how to best manage carbon sources and sinks in Interior Alaska. To support this we have surveyed relevant peer reviewed estimates of carbon stocks in aboveground and belowground biomass for Interior Alaska boreal ecosystems. We have also summarized methane and carbon dioxide fluxes from the same ecosystems. These data have been converted into the same units to facilitate comparison across ecosystem compartments. We identify potential changes in the carbon cycle with climate change and human disturbance including how compounding disturbances can affect the boreal system. Finally, we provide recommendations to address the challenges facing land managers in efforts to manage carbon cycle processes. The results of this study can be used for carbon cycle management in other locations within the boreal biome which encompass a broad distribution from 45° to 83° north.

The annual cycle of nitrate and net community production in surface waters of the Southern Ocean observed with SOCCOM profiling floats

NASA Astrophysics Data System (ADS)

Johnson, K. S.; Plant, J. N.; Sakamoto, C.; Coletti, L. J.; Sarmiento, J. L.; Riser, S.; Talley, L. D.

2016-12-01

Sixty profiling floats with ISUS and SUNA nitrate sensors have been deployed in the Southern Ocean (south of 30 degrees S) as part of the SOCCOM (Southern Ocean Carbon and Climate Observations and Modeling) program and earlier efforts. These floats have produced detailed records of the annual cycle of nitrate concentration throughout the region from the surface to depths near 2000 m. In surface waters, there are clear cycles in nitrate concentration that result from uptake of nitrate during austral spring and summer. These changes in nitrate concentration were used to compute the annual net community production over this region. NCP was computed using a simplified version of the approach detailed by Plant et al. (2016, Global Biogeochemical Cycles, 30, 859-879, DOI: 10.1002/2015GB005349). At the time the abstract was written 41 complete annual cycles were available from floats deployed before the austral summer of 2015/2016. After filtering the data to remove floats that crossed distinct frontal boundaries, floats with other anomalies, and floats in sub-tropical waters, 23 cycles were available. A preliminary assessment of the data yields an NCP of 2.8 +/- 0.95 (1 SD) mol C/m2/y after integrating to 100 m depth and converting nitrate uptake to carbon using the Redfield ratio. This preliminary assessment ignores vertical transport across the nitracline and is, therefore, a minimum estimate. The number of cycles available for analysis will increase rapidly, as 32 of the floats were deployed in the austral summer of 2015/2016 and have not yet been analyzed.

The Effects of Climate Sensitivity and Carbon Cycle Interactions on Mitigation Policy Stringency

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

Calvin, Katherine V.; Bond-Lamberty, Benjamin; Edmonds, James A.

2015-07-01

Climate sensitivity and climate-carbon cycle feedbacks interact to determine how global carbon and energy cycles will change in the future. While the science of these connections is well documented, their economic implications are not well understood. Here we examine the effect of climate change on the carbon cycle, the uncertainty in climate outcomes inherent in any given policy target, and the economic implications. We examine three policy scenarios—a no policy “Reference” (REF) scenario, and two policies that limit total radiative forcing—with four climate sensitivities using a coupled integrated assessment model. Like previous work, we find that, within a given scenario,more » there is a wide range of temperature change and sea level rise depending on the realized climate sensitivity. We expand on this previous work to show that temperature-related feedbacks on the carbon cycle result in more mitigation required as climate sensitivity increases. Thus, achieving a particular radiative forcing target becomes increasingly expensive as climate sensitivity increases.« less

The Path of Carbon in Photosynthesis XX. The Steady State

DOE R&D Accomplishments Database

Calvin, M.; Massini, Peter

1952-09-01

The separation of the phenomenon of photosynthesis in green plants into a photochemical reaction and into the light-dependent reduction of carbon dioxide is discussed, The reduction of carbon dioxide and the fate of the assimilated carbon were investigated with the help of the tracer technique (exposure of the planks to the radioactive C{sup 14}O{sub 2}) and of paper chromatography. A reaction cycle is proposed in which phosphoglyceric acid is the first isolable assimilations product. Analyses of the algal extracts which had assimilated radioactive carbon dioxide in a stationary condition ('steady-state' photosynthesis) for a long time provided further information concerning the proposed cycle and permitted the approximate estimation, for a number of compounds of what fraction of each compound was taking part in the cycle. The earlier supposition that light influences the respiration cycle was confirmed. The possibility of the assistance of {alpha}-lipoic acid, or of a related substance, in this influence and in the photosynthesis cycle, is discussed.

El Nino-southern oscillation related fluctuations of the marine carbon cycle

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

Winguth, A.M.E.; Heimann, M.; Kurz, K.D.

The yearly increase in global atmospheric carbon dioxide concentration is not constant, fluctuating around a mean growth rate. Some previous work has been done looking at the relationship of CO2 fluctuations with the El Nino-Southern Oscillation (ENSO) events in the Pacific. This paper describes the response of the three-dimensional ocean circulation model (Hamburg LSG) coupled on-line with a oceanic carbon cycle model (HAMOCC-3) to realistic wind and air temperature field anomalies. The focus is the marine carbon cycle and the interannual variations of carbon fluxes between ocean and atmosphere during the strong El Nino of 1982/83. 53 refs., 14 figs.

Carbon Cycling in Northern Peatlands

NASA Astrophysics Data System (ADS)

Schultz, Colin

2010-11-01

Northern peatlands span only 3 million square kilometers, about 3% of the terrestrial area of the globe, yet they represent a significant terrestrial sink for carbon dioxide. They are also important emitters of methane, an even more potent greenhouse gas. Despite their substantial role in the global carbon cycle, peatlands are not typically incorporated into global climate models. The AGU Monograph Carbon Cycling in Northern Peatlands, edited by Andrew J. Baird, Lisa R. Belyea, Xavier Comas, A. S. Reeve, and Lee D. Slater, looks at the disproportionate role peatlands play in the global carbon budget. In this interview, Eos talks with Andy Baird, University of Leeds, Leeds, United Kingdom.

State of the Carbon Cycle of North America: Overarching Findings

NASA Astrophysics Data System (ADS)

Mayes, M. A.; Reed, S.; Najjar, R.; Romero-Lankao, P.; Birdsey, R.

2016-12-01

This presentation will provide an overarching summary of the second "State of the Carbon Cycle of North America Report" (SOCCR2) from the perspective of the five editorial lead authors. The chapters of SOCCR2 represent a major update and much new material since the original report published a decade ago. The new report includes an overview of the North American carbon budget and future projections, the consequences of changes to the carbon budget, details of the carbon budget in major terrestrial and aquatic ecosystems and anthropogenic drivers, and implications for carbon management. The chapters focus on advances since the 2007 report, but also include new focus areas such as soil carbon, tribal lands, as well as greater emphasis on aquatic systems and the role of societal drivers and decision making on the carbon cycle. In addition, methane and the role of nitrogen will be considered to a greater extent than before. Each chapter also contains a section focusing on national and regional accounting to complement the overarching North American framework. In conclusion, SOCCR2 is expected to provide an updated assessment and a unique perspective on the carbon cycle, which will contribute to the next U.S. National Climate Assessment.

Can we bet on negative emissions to achieve the 2°C target even under strong carbon cycle feedbacks?

NASA Astrophysics Data System (ADS)

Tanaka, K.; Yamagata, Y.; Yokohata, T.; Emori, S.; Hanaoka, T.

2015-12-01

Negative emission technologies such as Bioenergy with Carbon dioxide Capture and Storage (BioCCS) play an ever more crucial role in meeting the 2°C stabilization target. However, such technologies are currently at their infancy and their future penetrations may fall short of the scale required to stabilize the warming. Furthermore, the overshoot in the mid-century prior to a full realization of negative emissions would give rise to a risk because such a temporal but excessive warming above 2°C might amplify itself by strengthening climate-carbon cycle feedbacks. It has not been extensively assessed yet how carbon cycle feedbacks might play out during the overshoot in the context of negative emissions. This study explores how 2°C stabilization pathways, in particular those which undergo overshoot, can be influenced by carbon cycle feedbacks and asks their climatic and economic consequences. We compute 2°C stabilization emissions scenarios under a cost-effectiveness principle, in which the total abatement costs are minimized such that the global warming is capped at 2°C. We employ a reduced-complexity model, the Aggregated Carbon Cycle, Atmospheric Chemistry, and Climate model (ACC2), which comprises a box model of the global carbon cycle, simple parameterizations of the atmospheric chemistry, and a land-ocean energy balance model. The total abatement costs are estimated from the marginal abatement cost functions for CO2, CH4, N2O, and BC.Our preliminary results show that, if carbon cycle feedbacks turn out to be stronger than what is known today, it would incur substantial abatement costs to keep up with the 2°C stabilization goal. Our results also suggest that it would be less expensive in the long run to plan for a 2°C stabilization pathway by considering strong carbon cycle feedbacks because it would cost more if we correct the emission pathway in the mid-century to adjust for unexpectedly large carbon cycle feedbacks during overshoot. Furthermore, our tentative results point to a key policy message: do not rely on negative emissions to achieve the 2°C target. It would make more sense to gear climate mitigation actions toward the stabilization target without betting on negative emissions because negative emissions might create large overshoot in case of strong feedbacks.

Net drainage effects on CO2 fluxes of a permafrost ecosystem through eddy-covariance measurements

NASA Astrophysics Data System (ADS)

Kittler, Fanny; Burjack, Ina; Zimov, Nikita; Zimov, Sergey; Heimann, Martin; Göckede, Mathias

2015-04-01

Permafrost landscapes in the Northern high latitudes with their massive organic carbon stocks are critically important for the global carbon cycle, yet feedback processes with the atmosphere under future climate conditions are uncertain. To improve the understanding of mechanisms and drivers dominating permafrost carbon cycling, we established a continuous observation program in moist tussock tundra ecosystem near Cherskiy in North-eastern Siberia (68.75°N, 161.33°E). The experiment has been designed to monitor carbon cycle fluxes at different scales with different approaches, including e.g. the eddy-covariance technique, and their environmental drivers. Recent observations started mid July 2013 and are still ongoing, while 'historic' measurements are available for the period 2002-2005. Since 2004 part of the observation area has been disturbed by a drainage ditch ring, altering the soil water conditions in the surrounding area in a way that is expected for degrading ice-rich permafrost under a warming climate. With parallel observations over the disturbed (drained) area and a reference area nearby, respectively, we aim to evaluate the disturbance effect on the carbon cycle budgets and the dominating biogeochemical mechanisms. Here, findings based on over 1.5 years of continuous eddy-covariance CO2 flux measurements (July 2013 - March 2015) for both observation areas are presented. Results show systematic shifts in the tundra ecosystem as a result of 10 years of disturbance in the drained area, with significant effects on biotic and abiotic site conditions as well as on the carbon cycle dynamics. Comparing the net budget fluxes between both observations areas indicates a reduction of the net sink strength for CO2 of the drained ecosystem during the summer season in comparison to natural conditions, mostly caused by reduced CO2 uptake with low water levels in late summer. Regarding the long-term CO2 uptake dynamics of the disturbance regime (2005 vs. 2013/14) the drained area has strongly rebounded from a strong reduction in NEE sink strength immediately following the disturbance. The observed significant increase in summertime uptake, has been caused mostly by an overall increase in the gross primary production. Based on the analysis of environmental drivers derived by in situ measurements and remote sensing products, this increase in summertime uptake is not linked to corresponding increases in air temperature, while there are some links to a greening of the ecosystem as observed in MODIS NDVI data. Finally, we present results on the role of the flux patterns during the non-growing season for the annual carbon budget, with a particular focus on the contributions of the shoulder seasons.

Understanding the Carbon Cycle : A Jigsaw Approach

NASA Astrophysics Data System (ADS)

Hastings, D. W.

2006-12-01

A thorough understanding of the carbon cycle is fundamental to understanding the eventual fate of CO2. To achieve this, students must understand individual processes, such as photosynthesis and respiration, as well as an integrated knowledge of how these processes relate to each other. In this "jigsaw" exercise, each student is assigned one five fundamental geochemical processes in the short- term carbon cycle to research and fully understand. In class, students first meet with others who have studied the same process to strengthen and deepen their understanding of this process. They then form teams of five students and explain to other students their particular process. In exchange, other students explain the other aspects of the carbon cycle. At the end of class all students will know about each of the five processes, and thus develop an integrated understanding of the entire carbon cycle. This approach is an efficient method for students to learn the material. As in a jigsaw puzzle, each student's part is essential for the full understanding of the carbon cycle. Since each student's part is essential, then each student is essential, which is what makes this strategy effective The jigsaw approach encourages listening, engagement, and collaboration by giving each member of the group an essential part to play in the academic activity.

Global convergence in the temperature sensitivity of respiration at ecosystem level.

PubMed

Mahecha, Miguel D; Reichstein, Markus; Carvalhais, Nuno; Lasslop, Gitta; Lange, Holger; Seneviratne, Sonia I; Vargas, Rodrigo; Ammann, Christof; Arain, M Altaf; Cescatti, Alessandro; Janssens, Ivan A; Migliavacca, Mirco; Montagnani, Leonardo; Richardson, Andrew D

2010-08-13

The respiratory release of carbon dioxide (CO(2)) from the land surface is a major flux in the global carbon cycle, antipodal to photosynthetic CO(2) uptake. Understanding the sensitivity of respiratory processes to temperature is central for quantifying the climate-carbon cycle feedback. We approximated the sensitivity of terrestrial ecosystem respiration to air temperature (Q(10)) across 60 FLUXNET sites with the use of a methodology that circumvents confounding effects. Contrary to previous findings, our results suggest that Q(10) is independent of mean annual temperature, does not differ among biomes, and is confined to values around 1.4 +/- 0.1. The strong relation between photosynthesis and respiration, by contrast, is highly variable among sites. The results may partly explain a less pronounced climate-carbon cycle feedback than suggested by current carbon cycle climate models.

A Brief Review of the Application of 14C in Terrestrial Carbon Cycle Studies

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

Guilderson, T; Mcfarlane, K

2009-10-22

An over-arching goal of the DOE TCP program is to understand the mechanistic controls over the fate, transport, and residence time of carbon in the terrestrial biosphere. Many of the modern process and modeling studies focus on seasonal to interannual variability. However, much of the carbon on the landscape and in soils is in separate reservoirs with turnover times that are multi-decadal to millennial. It is the controls on these longer term pools or reservoirs that is a critical unknown in the face of rising GHGs and climate change and uncertainties of the terrestrial biosphere as a future global sinkmore » or source of atmospheric CO{sub 2} [eg., Friedlingstein et al., 2006; Govindasamy et al., 2005; Thompson et al., 2004]. Radiocarbon measurements, in combination with other data, can provide insight into, and constraints on, terrestrial carbon cycling. Radiocarbon (t{sub 1/2} 5730yrs) is produced naturally in the stratosphere when secondary neutrons generated by cosmic rays collide with {sup 14}N atoms [Libby 1946; Arnold and Libby, 1949]. Upon formation, {sup 14}C is rapidly oxidized to CO and then to CO{sub 2}, and is incorporated into the carbon cycle. Due to anthropogenic activities, the amount of {sup 14}C in the atmosphere doubled in the mid/late 1950s and early 1960s from its preindustrial value of {sup 14}C/{sup 12}C ratio of 1.18 x 10{sup -12} [eg., Nydal and Lovseth, 1983]. Following the atmospheric weapons test ban in 1963, the {sup 14}C/{sup 12}C ratio, has decreased due to the net isotopic exchange between the ocean and terrestrial biosphere [eg., Levin and Hessheimer, 2000] and a dilution effect due to the burning of {sup 14}C-free fossil fuel carbon, the 'Suess Effect' [Suess, 1955]. In the carbon cycle literature, radiocarbon measurements are generally reported as {Delta}{sup 14}C, which includes a correction for mass dependent fractionation [Stuiver and Polach, 1977]. In the context of carbon cycle studies radiocarbon measurements can be used to determine the 'age' and rate of change of carbon stocks or as a biogeochemical tracer to elucidate processes and pathways. It is this dual nature that can be exploited across scales in space (individual plant, plot or research site, ecosystem, regional, and global) and time (days to millennia). For example, across regional scales, {Delta}{sup 14}C measurements of atmosphere CO{sub 2} can be used to attribute carbon dioxide to sources (e.g., respiration vs. fossil fuel emissions) or sinks ( e.g,. photosynthesis), which cannot be readily inferred from concentration, net flux measurements, or {delta}{sup 13}CO{sub 2} [eg. Graven et al., 2009; Levin and Hessheimer, 2000; Turnbull et al., 2007]. At smaller scales, similar analyses can be used to elucidate the source, and 'age' of the below ground component undergoing heterotrophic respiration. Net (biome or ecosystem) uptake of carbon is the difference of two large fluxes: photosynthesis and respiration. Carbon fixation by photosynthesis is, to a large extent, a single process with theoretical underpinnings. On the other-hand, net ecosystem or biome respiration integrates microbial (heterotrophic) and plant (autotrophic) respiration. Eddy covariance methods can be used to estimate bulk CO{sub 2} fluxes but they cannot discriminate the process nor the source of the respired CO{sub 2}. It is these processes that are parameterized in predictive models and contribute to the uncertainty in the climate forcing effect of the carbon cycle in the future [Friedlingstein et al., 2006; Heimann and Reichstein, 2008].« less

Measurements and modeling of CO 2 concentration and isotopes to improve process-level understanding of Arctic and boreal carbon cycling. Final Report

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

Keeling, Ralph F.

The major goal of this project was to improve understanding of processes that control the exchanges of CO 2 between the atmosphere and the land biosphere on decadal and longer time scales. The approach involves measuring the changes in atmospheric CO 2 concentration and the isotopes of CO 2 ( 13C/ 12C and 18O/ 16O) at background stations and uses these and other datasets to challenge and improve numerical models of the earth system. The project particularly emphasized the use of these data to improve understanding of changes occurring in boreal and arctic ecosystems over the past 50 years andmore » to seek from these data improved understanding of large-scale processes impacting carbon cycling, such as the responses to warming, CO 2 fertilization, and disturbance. The project also led to advances in the understanding of changes in water-use efficiency of land ecosystems globally based on trends in 13C/ 12C. The core element of this project was providing partial support for continuing measurements of CO 2 concentrations and isotopes from the Scripps CO 2 program, initiated by C. D. Keeling in the 1960s. The measurements included analysis of flasks collected at an array of ten stations distributed from the Arctic to the Antarctic. The project also supported modeling studies and interpretive work to help understand the origins of the large ~50% increase in the amplitude of the atmospheric CO 2 cycle detected at high northern latitudes between 1960 and present and to understand the long-term trend in carbon 13C/ 12C of CO 2. The seasonal cycle work was advanced through collaborations with colleagues at MPI Jena and Imperial College« less

Impact of hydrological variations on modeling of peatland CO2 fluxes: Results from the North American Carbon Program site synthesis

NASA Astrophysics Data System (ADS)

Sulman, Benjamin N.; Desai, Ankur R.; Schroeder, Nicole M.; Ricciuto, Dan; Barr, Alan; Richardson, Andrew D.; Flanagan, Lawrence B.; Lafleur, Peter M.; Tian, Hanqin; Chen, Guangsheng; Grant, Robert F.; Poulter, Benjamin; Verbeeck, Hans; Ciais, Philippe; Ringeval, Bruno; Baker, Ian T.; Schaefer, Kevin; Luo, Yiqi; Weng, Ensheng

2012-03-01

Northern peatlands are likely to be important in future carbon cycle-climate feedbacks due to their large carbon pools and vulnerability to hydrological change. Use of non-peatland-specific models could lead to bias in modeling studies of peatland-rich regions. Here, seven ecosystem models were used to simulate CO2fluxes at three wetland sites in Canada and the northern United States, including two nutrient-rich fens and one nutrient-poor,sphagnum-dominated bog, over periods between 1999 and 2007. Models consistently overestimated mean annual gross ecosystem production (GEP) and ecosystem respiration (ER) at all three sites. Monthly flux residuals (simulated - observed) were correlated with measured water table for GEP and ER at the two fen sites, but were not consistently correlated with water table at the bog site. Models that inhibited soil respiration under saturated conditions had less mean bias than models that did not. Modeled diurnal cycles agreed well with eddy covariance measurements at fen sites, but overestimated fluxes at the bog site. Eddy covariance GEP and ER at fens were higher during dry periods than during wet periods, while models predicted either the opposite relationship or no significant difference. At the bog site, eddy covariance GEP did not depend on water table, while simulated GEP was higher during wet periods. Carbon cycle modeling in peatland-rich regions could be improved by incorporating wetland-specific hydrology and by inhibiting GEP and ER under saturated conditions. Bogs and fens likely require distinct plant and soil parameterizations in ecosystem models due to differences in nutrients, peat properties, and plant communities.

Toward a Mexican eddy covariance network for carbon cycle science

NASA Astrophysics Data System (ADS)

Vargas, Rodrigo; Yépez, Enrico A.

2011-09-01

First Annual MexFlux Principal Investigators Meeting; Hermosillo, Sonora, Mexico, 4-8 May 2011; The carbon cycle science community has organized a global network, called FLUXNET, to measure the exchange of energy, water, and carbon dioxide (CO2) between the ecosystems and the atmosphere using the eddy covariance technique. This network has provided unprecedented information for carbon cycle science and global climate change but is mostly represented by study sites in the United States and Europe. Thus, there is an important gap in measurements and understanding of ecosystem dynamics in other regions of the world that are seeing a rapid change in land use. Researchers met under the sponsorship of Red Temática de Ecosistemas and Consejo Nacional de Ciencia y Tecnologia (CONACYT) to discuss strategies to establish a Mexican eddy covariance network (MexFlux) by identifying researchers, study sites, and scientific goals. During the meeting, attendees noted that 10 study sites have been established in Mexico with more than 30 combined years of information. Study sites span from new sites installed during 2011 to others with 9 to 6 years of measurements. Sites with the longest span measurements are located in Baja California Sur (established by Walter Oechel in 2002) and Sonora (established by Christopher Watts in 2005); both are semiarid ecosystems. MexFlux sites represent a variety of ecosystem types, including Mediterranean and sarcocaulescent shrublands in Baja California; oak woodland, subtropical shrubland, tropical dry forest, and a grassland in Sonora; tropical dry forests in Jalisco and Yucatan; a managed grassland in San Luis Potosi; and a managed pine forest in Hidalgo. Sites are maintained with an individual researcher's funds from Mexican government agencies (e.g., CONACYT) and international collaborations, but no coordinated funding exists for a long-term program.

Ocean Carbon Flux, Transport, and Burial Within the Western and Eastern US Coastal Zones

NASA Technical Reports Server (NTRS)

McWilliams, James C.; Moisan, John R.; Haidvogel, Dale B.; Miller, Arthur J.; Cornuelle, Bruce; Stolzenbach, Keith D.

2004-01-01

This project has been to develop and apply a regional. eddy-resolving circulation and biogeochemistry model of both the western and eastern U.S. coastal regions, capable of simulating the processes that control the carbon cycle. Validation has been by statistical comparison with analyses from various satellite measurements, including those from EOS sensors, as well as from in situ measurements. Sensitivity studies were carried out to investigate how the coastal ecosystem and biogeochemical cycles respond to changes in climate, large-scale eutrophication from indus- trial pollution, and other anthropogenic induced changes. The research has been conducted in collaboration with research groups at UCLA. NASA/GSFC (Wallops), Rutgers, and SIO. Overall. the project was focused on several key modeling issues, each of which tie back into completing the primary task of developing a coastal carbon model for both the eastern and western US. coasts. Individual groups within the entire program are still collaborating to address these specific tasks. These include: implementation of the coupled circulation/biogeochemical model within the U.S. West Coast. including high-resolution, embedded subdomains for the Southern California Bight and Monterey Bay region; development of a biogeochemical model with resolved carbon, nitrogen and oxygen cycles; development of data assimilation techniques for use of satellite data sets; reconfiguration of the model domain to U.S. East Coast; development of coastal forcing fields: development of methods to compare the model against remotely sensed data; and, the test of model sensitivity to environmental conditions. Below, we present a summary of the progress made toward achieving these soak. Because this has been a multi-institutional, collaborative effort, we note the groups involved with particular activities.

Carbon Cycle 2.0: Jay Keasling: Biofuels

ScienceCinema

Jay Keasling

2017-12-09

Feb. 4, 2010: Humanity emits more carbon into the atmosphere than natural processes are able to remove - an imbalance with negative consequences. Carbon Cycle 2.0 is a Berkeley Lab initiative to provide the science needed to restore this balance by integrating the Labs diverse research activities and delivering creative solutions toward a carbon-neutral energy future.

Carbon Cycle 2.0: Nitash Balsara: Energy Storage

ScienceCinema

Nitash Balsara

2017-12-09

Feb. 4, 2010: Humanity emits more carbon into the atmosphere than natural processes are able to remove - an imbalance with negative consequences. Carbon Cycle 2.0 is a Berkeley Lab initiative to provide the science needed to restore this balance by integrating the Labs diverse research activities and delivering creative solutions toward a carbon-neutral energy future.

Carbon Cycle 2.0: Ramamoorthy Ramesh: Low-cost Solar

ScienceCinema

Ramamoorthy Ramesh:

2017-12-09

Feb. 4, 2010: Humanity emits more carbon into the atmosphere than natural processes are able to remove - an imbalance with negative consequences. Carbon Cycle 2.0 is a Berkeley Lab initiative to provide the science needed to restore this balance by integrating the Labs diverse research activities and delivering creative solutions toward a carbon-neutral energy future.

Carbon Cycle 2.0: Robert Cheng and Juan Meza

ScienceCinema

Robert Cheng and Juan Meza

2017-12-09

Feb. 4, 2010: Humanity emits more carbon into the atmosphere than natural processes are able to remove - an imbalance with negative consequences. Carbon Cycle 2.0 is a Berkeley Lab initiative to provide the science needed to restore this balance by integrating the Labs diverse research activities and delivering creative solutions toward a carbon-neutral energy future.

Carbon Cycle 2.0: Robert Cheng and Juan Meza

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

Robert Cheng and Juan Meza

2010-02-16

Feb. 4, 2010: Humanity emits more carbon into the atmosphere than natural processes are able to remove - an imbalance with negative consequences. Carbon Cycle 2.0 is a Berkeley Lab initiative to provide the science needed to restore this balance by integrating the Labs diverse research activities and delivering creative solutions toward a carbon-neutral energy future.

40 CFR Table 7 to Subpart Ppp of... - Process Vents From Continuous Unit Operations-Monitoring, Recordkeeping, and Reporting Requirements

Code of Federal Regulations, 2013 CFR

2013-07-01

... regeneration stream mass or volumetric flow during carbon bed regeneration cycle; and temperature of the carbon bed after regeneration (and within 15 minutes of completing any cooling cycle(s)) Maximum mass or...

Carbon Dynamics and Export from Flooded Wetlands: A Modeling Approach

EPA Science Inventory

Described in this article is development and validation of a process based model for carbon cycling in flooded wetlands, called WetQual-C. The model considers various biogeochemical interactions affecting C cycling, greenhouse gas emissions, organic carbon export and retention. ...

Interactions between land use change and carbon cycle feedbacks: Land Use and Carbon Cycle Feedbacks

DOE PAGES

Mahowald, Natalie M.; Randerson, James T.; Lindsay, Keith; ...

2017-01-23

We explore the role of human land use and land cover change (LULCC) in modifying the terrestrial carbon budget in simulations forced by Representative Concentration Pathway 8.5, extended to year 2300 by using the Community Earth System Model, . Overall, conversion of land (e.g., from forest to croplands via deforestation) results in a model-estimated, cumulative carbon loss of 490 Pg C between 1850 and 2300, larger than the 230 Pg C loss of carbon caused by climate change over this same interval. The LULCC carbon loss is a combination of a direct loss at the time of conversion and anmore » indirect loss from the reduction of potential terrestrial carbon sinks. Approximately 40% of the carbon loss associated with LULCC in the simulations arises from direct human modification of the land surface; the remaining 60% is an indirect consequence of the loss of potential natural carbon sinks. Because of the multicentury carbon cycle legacy of current land use decisions, a globally averaged amplification factor of 2.6 must be applied to 2015 land use carbon losses to adjust for indirect effects. This estimate is 30% higher when considering the carbon cycle evolution after 2100. Most of the terrestrial uptake of anthropogenic carbon in the model occurs from the influence of rising atmospheric CO 2 on photosynthesis in trees, and thus, model-projected carbon feedbacks are especially sensitive to deforestation.« less

Interactions between land use change and carbon cycle feedbacks: Land Use and Carbon Cycle Feedbacks

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

Mahowald, Natalie M.; Randerson, James T.; Lindsay, Keith

We explore the role of human land use and land cover change (LULCC) in modifying the terrestrial carbon budget in simulations forced by Representative Concentration Pathway 8.5, extended to year 2300 by using the Community Earth System Model, . Overall, conversion of land (e.g., from forest to croplands via deforestation) results in a model-estimated, cumulative carbon loss of 490 Pg C between 1850 and 2300, larger than the 230 Pg C loss of carbon caused by climate change over this same interval. The LULCC carbon loss is a combination of a direct loss at the time of conversion and anmore » indirect loss from the reduction of potential terrestrial carbon sinks. Approximately 40% of the carbon loss associated with LULCC in the simulations arises from direct human modification of the land surface; the remaining 60% is an indirect consequence of the loss of potential natural carbon sinks. Because of the multicentury carbon cycle legacy of current land use decisions, a globally averaged amplification factor of 2.6 must be applied to 2015 land use carbon losses to adjust for indirect effects. This estimate is 30% higher when considering the carbon cycle evolution after 2100. Most of the terrestrial uptake of anthropogenic carbon in the model occurs from the influence of rising atmospheric CO 2 on photosynthesis in trees, and thus, model-projected carbon feedbacks are especially sensitive to deforestation.« less

Discussion of Refrigeration Cycle Using Carbon Dioxide as Refrigerant

NASA Astrophysics Data System (ADS)

Ji, Amin; Sun, Miming; Li, Jie; Yin, Gang; Cheng, Keyong; Zhen, Bing; Sun, Ying

Nowadays, the problem of the environment goes worse, it urges people to research and study new energy-saving and environment-friendly refrigerants, such as carbon dioxide, at present, people do research on carbon dioxide at home and abroad. This paper introduces the property of carbon dioxide as a refrigerant, sums up and analyses carbon dioxide refrigeration cycles, and points out the development and research direction in the future.

Carbon stocks and changes of dead organic matter in China's forests

Treesearch

Jianxiao Zhu; Huifeng Hu; Shengli Tao; Xiulian Chi; Peng Li; Lai Jiang; Chengjun Ji; Jiangling Zhu; Zhiyao Tang; Yude Pan; Richard A. Birdsey; Xinhua He; Jingyun Fang

2017-01-01

Forests play an important role in global carbon cycles. However, the lack of available information on carbon stocks in dead organic matter, including woody debris and litter, reduces the reliability of assessing the carbon cycles in entire forest ecosystems. Here we estimate that the national DOM carbon stock in the period of 2004–2008 is 925 ± 54 Tg, with an average...

Effects of Carbon Structure and Surface Oxygen on the Carbon's Performance as the Anode in Lithium-Ion Battery Determined

NASA Technical Reports Server (NTRS)

Hung, Ching-Cheh

2000-01-01

Four carbon materials (C1, C2, C3, and C4) were tested electrochemically at the NASA Glenn Research Center at Lewis Field to determine their performance in lithium-ion batteries. They were formed as shown in the figure. This process caused very little carbon loss. Products C1 and C3 contained very little oxygen because of the final overnight heating at 540 C. Products C2 and C4, on the other hand, contained small amounts of basic oxide. The electrochemical test involved cycles of lithium intercalation and deintercalation using C/saturated LiI-50/50 (vol %) ethylene carbonate (EC) and dimethyl carbonate (DMC)/Li half cell. The cycling test, which is summarized in the table, resulted in three major conclusions. The capacity of the carbon with a basic oxide surface converges to a constant 1. value quickly (within 4 cycles), possibly because the oxide prevents solvent from entering the carbon structure and, therefore, prolongs the carbon s cycle life. Under certain conditions, the disordered carbon can store more lithium than its 2. precursor. These samples and their precursor can intercalate at 200 mA/g and deintercalate at 3. a rate of 2000 mA/g without significant capacity loss.

Results of the pollution reduction technology program for turboprop engines

NASA Technical Reports Server (NTRS)

Mularz, E. J.

1976-01-01

A program was performed to evolve and demonstrate advanced combustor technology aimed at achieving the 1979 EPA standards for turboprop engines (Class P2). The engine selected for this program was the 501-D22A turboprop. Three combustor concepts were designed and tested in a combustor rig at the exact combustor operating conditions of the 50-D22A engine over the EPA landing-takeoff cycle. Each combustor concept exhibited pollutant emissions well below the EPA standards, achieving substantial reductions in unburned hydrocarbons, carbon monoxide, and smoke emissions compared with emissions from the production combustor of this engine. Oxides of nitrogen emissions remained well below the EPA standards, also.

Analysis of Co-spatial UV-Optical STIS Spectra of Planetary Nebulae From HST Cycle 19 GO 12600

NASA Astrophysics Data System (ADS)

Miller, Timothy R.; Henry, Richard B. C.; Dufour, Reginald J.; Kwitter, Karen B.; Shaw, Richard A.; Balick, Bruce; Corradi, Romano

2015-01-01

We present an analysis of five spatially resolved planetary nebulae (PNe), NGC 5315, NGC 5882, NGC 7662, IC 2165, and IC 3568, from observations in the Cycle 19 program GO 12600 using HST STIS. Details of the observations and data are presented in the poster by Dufour et al. in this session. These five observations cover the wavelength range 1150-10,270 Å with 0.2 and 0.5 arcsec wide slits, and are co-spatial to 0.1 arcsec along a 25 arcsec length across each nebula. This unprecedented resolution in both wavelength and spatial coverage enabled detailed studies of physical conditions and abundances from UV line ion emissions (compared to optical lines). We first analyzed the low- and moderate-resolution UV emission lines of carbon using the resolved lines of C III] 1906.68 and 1908.73, which yielded a direct measurement of the density within the volume occupied by doubly-ionized carbon and other similar co-spatial ions. Next, each PN spectrum was divided into spatial sub-regions in order to assess inferred density variations among the sub-regions along the entire slit. Variations in electron temperature and chemical abundances were also probed. Lastly, these nebulae were modeled in detail with the photoionization code CLOUDY. This modeling tested different density profiles in order to reproduce the observed density variations and temperature fluctuations, and constrain central star parameters. We gratefully acknowledge generous support from NASA through grants related to the Cycle 19 program GO 12600, as well as from the University of Oklahoma.

Oceanic crustal carbon cycle drives 26-million-year atmospheric carbon dioxide periodicities.

PubMed

Müller, R Dietmar; Dutkiewicz, Adriana

2018-02-01

Atmospheric carbon dioxide (CO 2 ) data for the last 420 million years (My) show long-term fluctuations related to supercontinent cycles as well as shorter cycles at 26 to 32 My whose origin is unknown. Periodicities of 26 to 30 My occur in diverse geological phenomena including mass extinctions, flood basalt volcanism, ocean anoxic events, deposition of massive evaporites, sequence boundaries, and orogenic events and have previously been linked to an extraterrestrial mechanism. The vast oceanic crustal carbon reservoir is an alternative potential driving force of climate fluctuations at these time scales, with hydrothermal crustal carbon uptake occurring mostly in young crust with a strong dependence on ocean bottom water temperature. We combine a global plate model and oceanic paleo-age grids with estimates of paleo-ocean bottom water temperatures to track the evolution of the oceanic crustal carbon reservoir over the past 230 My. We show that seafloor spreading rates as well as the storage, subduction, and emission of oceanic crustal and mantle CO 2 fluctuate with a period of 26 My. A connection with seafloor spreading rates and equivalent cycles in subduction zone rollback suggests that these periodicities are driven by the dynamics of subduction zone migration. The oceanic crust-mantle carbon cycle is thus a previously overlooked mechanism that connects plate tectonic pulsing with fluctuations in atmospheric carbon and surface environments.

Oceanic crustal carbon cycle drives 26-million-year atmospheric carbon dioxide periodicities

PubMed Central

Müller, R. Dietmar; Dutkiewicz, Adriana

2018-01-01

Atmospheric carbon dioxide (CO2) data for the last 420 million years (My) show long-term fluctuations related to supercontinent cycles as well as shorter cycles at 26 to 32 My whose origin is unknown. Periodicities of 26 to 30 My occur in diverse geological phenomena including mass extinctions, flood basalt volcanism, ocean anoxic events, deposition of massive evaporites, sequence boundaries, and orogenic events and have previously been linked to an extraterrestrial mechanism. The vast oceanic crustal carbon reservoir is an alternative potential driving force of climate fluctuations at these time scales, with hydrothermal crustal carbon uptake occurring mostly in young crust with a strong dependence on ocean bottom water temperature. We combine a global plate model and oceanic paleo-age grids with estimates of paleo-ocean bottom water temperatures to track the evolution of the oceanic crustal carbon reservoir over the past 230 My. We show that seafloor spreading rates as well as the storage, subduction, and emission of oceanic crustal and mantle CO2 fluctuate with a period of 26 My. A connection with seafloor spreading rates and equivalent cycles in subduction zone rollback suggests that these periodicities are driven by the dynamics of subduction zone migration. The oceanic crust-mantle carbon cycle is thus a previously overlooked mechanism that connects plate tectonic pulsing with fluctuations in atmospheric carbon and surface environments. PMID:29457135

The Contemporary Carbon Cycle

NASA Astrophysics Data System (ADS)

Houghton, R. A.

2003-12-01

The global carbon cycle refers to the exchanges of carbon within and between four major reservoirs: the atmosphere, the oceans, land, and fossil fuels. Carbon may be transferred from one reservoir to another in seconds (e.g., the fixation of atmospheric CO2 into sugar through photosynthesis) or over millennia (e.g., the accumulation of fossil carbon (coal, oil, gas) through deposition and diagenesis of organic matter). This chapter emphasizes the exchanges that are important over years to decades and includes those occurring over the scale of months to a few centuries. The focus will be on the years 1980-2000 but our considerations will broadly include the years ˜1850-2100. Chapter 8.09, deals with longer-term processes that involve rates of carbon exchange that are small on an annual timescale (weathering, vulcanism, sedimentation, and diagenesis).The carbon cycle is important for at least three reasons. First, carbon forms the structure of all life on the planet, making up ˜50% of the dry weight of living things. Second, the cycling of carbon approximates the flows of energy around the Earth, the metabolism of natural, human, and industrial systems. Plants transform radiant energy into chemical energy in the form of sugars, starches, and other forms of organic matter; this energy, whether in living organisms or dead organic matter, supports food chains in natural ecosystems as well as human ecosystems, not the least of which are industrial societies habituated (addicted?) to fossil forms of energy for heating, transportation, and generation of electricity. The increased use of fossil fuels has led to a third reason for interest in the carbon cycle. Carbon, in the form of carbon dioxide (CO2) and methane (CH4), forms two of the most important greenhouse gases. These gases contribute to a natural greenhouse effect that has kept the planet warm enough to evolve and support life (without the greenhouse effect the Earth's average temperature would be -33°C). Additions of greenhouse gases to the atmosphere from industrial activity, however, are increasing the concentrations of these gases, enhancing the greenhouse effect, and starting to warm the Earth.The rate and extent of the warming depend, in part, on the global carbon cycle. If the rate at which the oceans remove CO2 from the atmosphere were faster, e.g., concentrations of CO2 would have increased less over the last century. If the processes removing carbon from the atmosphere and storing it on land were to diminish, concentrations of CO2 would increase more rapidly than projected on the basis of recent history. The processes responsible for adding carbon to, and withdrawing it from, the atmosphere are not well enough understood to predict future levels of CO2 with great accuracy. These processes are a part of the global carbon cycle.Some of the processes that add carbon to the atmosphere or remove it, such as the combustion of fossil fuels and the establishment of tree plantations, are under direct human control. Others, such as the accumulation of carbon in the oceans or on land as a result of changes in global climate (i.e., feedbacks between the global carbon cycle and climate), are not under direct human control except through controlling rates of greenhouse gas emissions and, hence, climatic change. Because CO2 has been more important than all of the other greenhouse gases under human control, combined, and is expected to continue so in the future, understanding the global carbon cycle is a vital part of managing global climate.This chapter addresses, first, the reservoirs and natural flows of carbon on the earth. It then addresses the sources of carbon to the atmosphere from human uses of land and energy and the sinks of carbon on land and in the oceans that have kept the atmospheric accumulation of CO2 lower than it would otherwise have been. The chapter describes changes in the distribution of carbon among the atmosphere, oceans, and terrestrial ecosystems over the past 150 years as a result of human-induced emissions of carbon. The processes responsible for sinks of carbon on land and in the sea are reviewed from the perspective of feedbacks, and the chapter concludes with some prospects for the future.Earlier comprehensive summaries of the global carbon cycle include studies by Bolin et al. (1979, 1986), Woodwell and Pecan (1973), Bolin (1981), NRC (1983), Sundquist and Broecker (1985), and Trabalka (1985). More recently, the Intergovernmental Panel on Climate Change (IPCC) has summarized information on the carbon cycle in the context of climate change ( Watson et al., 1990; Schimel et al., 1996; Prentice et al., 2001). The basic aspects of the global carbon cycle have been understood for decades, but other aspects, such as the partitioning of the carbon sink between land and ocean, are being re-evaluated continuously with new data and analyses. The rate at which new publications revise estimates of these carbon sinks and re-evaluate the mechanisms that control the magnitude of the sinks suggests that portions of this review will be out of date by the time of publication.

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

NASA Astrophysics Data System (ADS)

Zeebe, R. E.

2012-01-01

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

40 CFR Table 2 to Subpart Uuuu of... - Operating Limits

Code of Federal Regulations, 2013 CFR

2013-07-01

... values established during the compliance demonstration. 7. carbon absorber maintain the regeneration frequency, total regeneration adsorber stream mass or volumetric flow during carbon bed regeneration, and temperature of the carbon bed after regeneration (and within 15 minutes of completing any cooling cycle(s...

40 CFR Table 2 to Subpart Uuuu of... - Operating Limits

Code of Federal Regulations, 2012 CFR

2012-07-01

... values established during the compliance demonstration. 7. carbon absorber maintain the regeneration frequency, total regeneration adsorber stream mass or volumetric flow during carbon bed regeneration, and temperature of the carbon bed after regeneration (and within 15 minutes of completing any cooling cycle(s...

40 CFR Table 2 to Subpart Uuuu of... - Operating Limits

Code of Federal Regulations, 2014 CFR

2014-07-01

... values established during the compliance demonstration. 7. carbon absorber maintain the regeneration frequency, total regeneration adsorber stream mass or volumetric flow during carbon bed regeneration, and temperature of the carbon bed after regeneration (and within 15 minutes of completing any cooling cycle(s...

Urbanization and the Carbon Cycle: Synthesis of Ongoing Research

NASA Astrophysics Data System (ADS)

Gurney, K. R.; Duren, R. M.; Hutyra, L.; Ehleringer, J. R.; Patarasuk, R.; Song, Y.; Huang, J.; Davis, K.; Kort, E. A.; Shepson, P. B.; Turnbull, J. C.; Lauvaux, T.; Rao, P.; Eldering, A.; Miller, C. E.; Wofsy, S.; McKain, K.; Mendoza, D. L.; Lin, J. C.; Sweeney, C.; Miles, N. L.; Richardson, S.; Cambaliza, M. O. L.

2015-12-01

Given the explosive growth in urbanization and its dominant role in current and future global greenhouse gas emissions, urban areas have received increasing research attention from the carbon cycle science community. The emerging focus is driven by the increasingly dense atmospheric observing capabilities - ground and space-based - in addition to the rising profile of cities within international climate change policymaking. Dominated by anthropogenic emissions, urban carbon cycle research requires a cross-disciplinary perspective with contributions from disciplines such as engineering, economics, social theory, and atmospheric science. We review the recent results from a sample of the active urban carbon research efforts including the INFLUX experiment (Indianapolis), the Megacity carbon project (Los Angeles), Salt Lake City, and Boston. Each of these efforts represent unique approaches in pursuit of different scientific and policy questions and assist in setting priorities for future research. From top-down atmospheric measurement systems to bottom-up estimation, these research efforts offer a view of the challenges and opportunities in urban carbon cycle research.

Carbon-silicon core-shell nanowires as high capacity electrode for lithium ion batteries.

PubMed

Cui, Li-Feng; Yang, Yuan; Hsu, Ching-Mei; Cui, Yi

2009-09-01

We introduce a novel design of carbon-silicon core-shell nanowires for high power and long life lithium battery electrodes. Amorphous silicon was coated onto carbon nanofibers to form a core-shell structure and the resulted core-shell nanowires showed great performance as anode material. Since carbon has a much smaller capacity compared to silicon, the carbon core experiences less structural stress or damage during lithium cycling and can function as a mechanical support and an efficient electron conducting pathway. These nanowires have a high charge storage capacity of approximately 2000 mAh/g and good cycling life. They also have a high Coulmbic efficiency of 90% for the first cycle and 98-99.6% for the following cycles. A full cell composed of LiCoO(2) cathode and carbon-silicon core-shell nanowire anode is also demonstrated. Significantly, using these core-shell nanowires we have obtained high mass loading and an area capacity of approximately 4 mAh/cm(2), which is comparable to commercial battery values.

Superior performance of nanoscaled Fe3O4 as anode material promoted by mosaicking into porous carbon framework

NASA Astrophysics Data System (ADS)

Wan, Wang; Wang, Chao; Zhang, Weidong; Chen, Jitao; Zhou, Henghui; Zhang, Xinxiang

2014-01-01

A nanoscale Fe3O4/porous carbon-multiwalled carbon nanotubes (MWCNTs) composite is synthesized through a simple hard-template method by using Fe2O3 nanoparticles as the precursor and SiO2 nanoparticles as the template. The composite shows good cycle performance (941 mAh g-1 for the first cycle at 0.1 C, with 106% capacity retention at the 80th cycle) and high rate capability (71% capacity retained at 5 C rate). Its excellent electrical properties can be attributed to the porous carbon framework structure, which is composed of carbon and MWCNTs. In this composite, the porous structure provides space for the change in Fe3O4 volume during cycling and shortens the lithium ion diffusion distance, the MWCNTs increase the electron conductivity, and the carbon coating reduces the risk of side reactions. The results provide clear evidences for the utility of porous carbon framework to improve the electrochemical performances of nanosized transition-metal oxides as anode materials for lithium-ion batteries.

Assessing spatiotemporal changes in forest carbon turnover times in observational data and models

NASA Astrophysics Data System (ADS)

Yu, K.; Smith, W. K.; Trugman, A. T.; van Mantgem, P.; Peng, C.; Condit, R.; Anderegg, W.

2017-12-01

Forests influence global carbon and water cycles, biophysical land-atmosphere feedbacks, and atmospheric composition. The capacity of forests to sequester atmospheric CO2 in a changing climate depends not only on the response of carbon uptake (i.e., gross primary productivity) but also on the simultaneous change in carbon residence time. However, changes in carbon residence with climate change are uncertain, impacting the accuracy of predictions of future terrestrial carbon cycle dynamics. Here, we use long-term forest inventory data representative of tropical, temperate, and boreal forests; satellite-based estimates of net primary productivity and vegetation carbon stock; and six models from the Coupled Model Intercomparison Project Phase 5 (CMIP5) to investigate spatiotemporal trends in carbon residence time and its relation to climate. Forest inventory and satellite-based estimates of carbon residence time show a pervasive decreasing trend across global forests. In contrast, the CMIP5 models diverge in predicting historical and future trends in carbon residence time. Divergence across CMIP5 models indicate carbon turnover times are not well constrained by observations, which likely contributes to large variability in future carbon cycle projections.

Developing a Carbon Observing System

NASA Astrophysics Data System (ADS)

Moore, B., III

2015-12-01

There is a clear need to better understand and predict future climate change, so that science can more confidently inform climate policy, including adaptation planning and future mitigation strategies. Understanding carbon cycle feedbacks, and the relationship between emissions (fossil and land use) and the resulting atmospheric carbon dioxide (CO2) and methane (CH4) concentrations in a changing climate has been recognized as an important goal by the IPCC. The existing surface greenhouse gas observing networks provide accurate and precise measurements of background values, but they are not configured to target the extended, complex and dynamic regions of the carbon budget. Space Agencies around the globe are committed to CO2 and CH4 observations: GOSAT-1/2, OCO-2/3, MERLin, TanSat, and CarbonSat. In addition to these Low Earth Orbit (LEO) missions, a new mission in Geostationary Orbit (GEO), geoCARB, which would provide mapping-like measurements of carbon dioxide, methane, and carbon monoxide concentrations over major land areas, has been recently proposed to the NASA Venture Program. These pioneering missions do not provide the spatial/temporal coverage to answer the key carbon-climate questions at process relevant scales nor do they address the distribution and quantification of anthropogenic sources at urban scales. They do demonstrate, however, that a well-planned future system of system integrating space-based LEO and GEO missions with extensive in situ observations could provide the accuracy, spatial resolution, and coverage needed to address critical open issues in the carbon-climate system. Dr. Diana Wickland devoted enormous energy in developing a comprehensive apprioach to understand the global carbon cycle; she understood well that an integrated, coordinated, international approach is needed. This shines through in her recent contribution in co-chairing the team that produced the "CEOS Strategy for Carbon Observations from Space." A NASA-funded community workshop in March 2015 addressed issues and prioritzed a set of research and observational needs in the study of the Carbon-Climate System. This paper will refect upon the past 30 plus years of carbon research supported by NASA and Dr. Wickland's role, and it will conclude with the findings of the March 2015 Workshop.

Late Mississippian (Chesterian) carbonate to carbonate-clastic cycles in the eastern Illinois Basin

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

Smith, L.B.; Read, J.F.

1994-03-01

Late Mississippian (Chesterian) rocks of the eastern Illinois Basin in Kentucky and Indiana show depositional cycles (3--20 meters thick) composed of a range of facies deposited during the transition from carbonate-dominated deposition of the Middle Mississippian to the predominantly siliciclastic regime of the Pennsylvanian. Within the basal Ste. Genevieve Formation (30--70 meters thick) there are five predominantly carbonate cycles. Cycle bases vary from thin calcareous sandstone near the northern clastic source to ooid-quartz dolomitic pelletal grainstone and mudstone further south. Massive cross-bedded and channeled ooid-skeletal grainstones represent the cycle tops and are commonly capped by caliche and subaerial breccia, particularlymore » where there was no subsequent siliciclastic deposition. The cycles are interpreted to be driven by fourth-order (400 k.y.) glacio-eustatic sea-level fluctuations based on coincidence of the calculated cycle period with the long-term eccentricity signal, the Late Mississippian onset of Gondwana glaciation and cycle correlation over more than 100 kilometers. The breccia and caliche formed during lowstands, the siliciclastics, eolianites and dolomitic pelletal grainstones are transgressive facies and the ooid-skeletal grainstones represent sea-level highstands.« less

Incorporating phosphorus cycling into global modeling efforts: a worthwhile, tractable endeavor

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

Reed, Sasha C.; Yang, Xiaojuan; Thornton, Peter E.

2015-06-25

Myriad field, laboratory, and modeling studies show that nutrient availability plays a fundamental role in regulating CO 2 exchange between the Earth's biosphere and atmosphere, and in determining how carbon pools and fluxes respond to climatic change. Accordingly, global models that incorporate coupled climate-carbon cycle feedbacks made a significant advance with the introduction of a prognostic nitrogen cycle. Here we propose that incorporating phosphorus cycling represents an important next step in coupled climate-carbon cycling model development, particularly for lowland tropical forests where phosphorus availability is often presumed to limit primary production. We highlight challenges to including phosphorus in modeling effortsmore » and provide suggestions for how to move forward.« less

Incorporating phosphorus cycling into global modeling efforts: a worthwhile, tractable endeavor

USGS Publications Warehouse

Reed, Sasha C.; Yang, Xiaojuan; Thornton, Peter E.

2015-01-01

Myriad field, laboratory, and modeling studies show that nutrient availability plays a fundamental role in regulating CO2 exchange between the Earth's biosphere and atmosphere, and in determining how carbon pools and fluxes respond to climatic change. Accordingly, global models that incorporate coupled climate–carbon cycle feedbacks made a significant advance with the introduction of a prognostic nitrogen cycle. Here we propose that incorporating phosphorus cycling represents an important next step in coupled climate–carbon cycling model development, particularly for lowland tropical forests where phosphorus availability is often presumed to limit primary production. We highlight challenges to including phosphorus in modeling efforts and provide suggestions for how to move forward.

Carbon Cycle 2.0: Don DePaolo: Geo and Bio Sequestration

ScienceCinema

Don DePaolo:

2017-12-09

Feb. 4, 2010: Humanity emits more carbon into the atmosphere than natural processes are able to remove - an imbalance with negative consequences. Carbon Cycle 2.0 is a Berkeley Lab initiative to provide the science needed to restore this balance by integrating the Labs diverse research activities and delivering creative solutions toward a carbon-neutral energy future.

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

Price, Lynn

Lynn Price, LBNL scientist, speaks at the Carbon Cycle 2.0 kick-off symposium Feb. 2, 2010. We emit more carbon into the atmosphere than natural processes are able to remove - an imbalance with negative consequences. Carbon Cycle 2.0 is a Berkeley Lab initiative to provide the science needed to restore this balance by integrating the Labs diverse research activities and delivering creative solutions toward a carbon-neutral energy future.

Trailblazing the Carbon Cycle of Tropical Forests from Puerto Rico

Treesearch

Sandra Brown; Ariel Lugo

2017-01-01

We review the literature that led to clarifying the role of tropical forests in the global carbon cycle from a time when they were considered sources of atmospheric carbon to the time when they were found to be atmospheric carbon sinks. This literature originates from work conducted by US Forest Service scientists in Puerto Rico and their collaborators. It involves the...

The carbon dioxide cycle

USGS Publications Warehouse

James, P.B.; Hansen, G.B.; Titus, T.N.

2005-01-01

The seasonal CO2 cycle on Mars refers to the exchange of carbon dioxide between dry ice in the seasonal polar caps and gaseous carbon dioxide in the atmosphere. This review focuses on breakthroughs in understanding the process involving seasonal carbon dioxide phase changes that have occurred as a result of observations by Mars Global Surveyor. ?? 2004 COSPAR. Published by Elsevier Ltd. All rights reserved.

Chemical Oceanography and the Marine Carbon Cycle

NASA Astrophysics Data System (ADS)

Emerson, Steven; Hedges, John

The principles of chemical oceanography provide insight into the processes regulating the marine carbon cycle. The text offers a background in chemical oceanography and a description of how chemical elements in seawater and ocean sediments are used as tracers of physical, biological, chemical and geological processes in the ocean. The first seven chapters present basic topics of thermodynamics, isotope systematics and carbonate chemistry, and explain the influence of life on ocean chemistry and how it has evolved in the recent (glacial-interglacial) past. This is followed by topics essential to understanding the carbon cycle, including organic geochemistry, air-sea gas exchange, diffusion and reaction kinetics, the marine and atmosphere carbon cycle and diagenesis in marine sediments. Figures are available to download from www.cambridge.org/9780521833134. Ideal as a textbook for upper-level undergraduates and graduates in oceanography, environmental chemistry, geochemistry and earth science and a valuable reference for researchers in oceanography.

Carbon Corrosion in PEM Fuel Cells and the Development of Accelerated Stress Tests

DOE PAGES

Macauley, Natalia; Papadias, Dennis D.; Fairweather, Joseph; ...

2018-03-15

Here, carbon corrosion is an important degradation mechanism that can impair PEMFC performance through the destruction of catalyst connectivity, collapse of the electrode pore structure, loss of hydrophobic character, and an increase of the catalyst particle size. In this study, carbon corrosion was quantified in situ by measurement of carbon dioxide in the fuel cell exhaust gases through non-dispersive infrared spectroscopy during simulated drive cycle operations consisting of potential cycling with varying upper and lower potential limits. These studies were conducted for three different types of carbon supports. A reduction in the catalyst layer thickness was observed during a simulatedmore » drive cycle operation with a concomitant decrease in catalyst layer porosity, which led to performance losses due to increased mass transport limitations. The observed thickness reduction was primarily due to compaction of the catalyst layer, with the actual mass of carbon oxidation (loss) contributing only a small fraction (< 20%). The dynamics of carbon corrosion are presented along with a model that simulates the transient and dynamic corrosion rates observed in our experiments. Accelerated carbon corrosion stress tests are presented and their effects are compared to those observed for the drive cycle test.« less

Global redox cycle of biospheric carbon: Interaction of photosynthesis and earth crust processes.

PubMed

Ivlev, Alexander A

2015-11-01

A model of the natural global redox cycle of biospheric carbon is introduced. According to this model, carbon transfer between biosphere and geospheres is accompanied by a conversion of the oxidative forms, presented by CO2, bicarbonate and carbonate ions, into the reduced forms, produced in photosynthesis. The mechanism of carbon transfer is associated with two phases of movement of lithospheric plates. In the short-term orogenic phase, CO2 from the subduction (plates' collisions) zones fills the "atmosphere-hydrosphere" system, resulting in climate warming. In the long-term quiet (geosynclynal) phase, weathering and photosynthesis become dominant depleting the oxidative forms of carbon. The above asymmetric periodicity exerts an impact on climate, biodiversity, distribution of organic matter in sedimentary deposits, etc. Along with photosynthesis expansion, the redox carbon cycle undergoes its development until it reaches the ecological compensation point, at which CO2 is depleted to the level critical to support the growth and reproduction of plants. This occurred in the Permo-Carboniferous time and in the Neogene. Shorter-term perturbations of the global carbon cycle in the form of glacial-interglacial oscillations appear near the ecological compensation point. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Carbon Corrosion in PEM Fuel Cells and the Development of Accelerated Stress Tests

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

Macauley, Natalia; Papadias, Dennis D.; Fairweather, Joseph

Here, carbon corrosion is an important degradation mechanism that can impair PEMFC performance through the destruction of catalyst connectivity, collapse of the electrode pore structure, loss of hydrophobic character, and an increase of the catalyst particle size. In this study, carbon corrosion was quantified in situ by measurement of carbon dioxide in the fuel cell exhaust gases through non-dispersive infrared spectroscopy during simulated drive cycle operations consisting of potential cycling with varying upper and lower potential limits. These studies were conducted for three different types of carbon supports. A reduction in the catalyst layer thickness was observed during a simulatedmore » drive cycle operation with a concomitant decrease in catalyst layer porosity, which led to performance losses due to increased mass transport limitations. The observed thickness reduction was primarily due to compaction of the catalyst layer, with the actual mass of carbon oxidation (loss) contributing only a small fraction (< 20%). The dynamics of carbon corrosion are presented along with a model that simulates the transient and dynamic corrosion rates observed in our experiments. Accelerated carbon corrosion stress tests are presented and their effects are compared to those observed for the drive cycle test.« less

40 CFR Table 2 to Subpart Uuuu of... - Operating Limits

Code of Federal Regulations, 2011 CFR

2011-07-01

... established during the compliance demonstration. 7. carbon absorber maintain the regeneration frequency, total regeneration adsorber stream mass or volumetric flow during carbon bed regeneration, and temperature of the carbon bed after regeneration (and within 15 minutes of completing any cooling cycle(s)) for each...

40 CFR Table 2 to Subpart Uuuu of... - Operating Limits

Code of Federal Regulations, 2010 CFR

2010-07-01

... established during the compliance demonstration. 7. carbon absorber maintain the regeneration frequency, total regeneration adsorber stream mass or volumetric flow during carbon bed regeneration, and temperature of the carbon bed after regeneration (and within 15 minutes of completing any cooling cycle(s)) for each...

Carbon Stars In Andromeda. II. Demographics and Photometric Properties

NASA Astrophysics Data System (ADS)

Guhathakurta, Puragra; Hamren, K.; Dorman, C.; Toloba, E.; Seth, A.; Dalcanton, J.; Nayak, A.; PHAT Collaboration; SPLASH Collaboration

2014-01-01

This is the second of two talks about a sample of newly-discovered carbon stars in the Andromeda galaxy (M31). As explained in the first talk, these stars were identified on the basis of their spectroscopic characteristics using Keck/DEIMOS spectra obtained as part of the Spectroscopic and Photometric Landscape of Andromeda's Stellar Halo (SPLASH) survey. We explore the physical properties of strong and weak carbon stars using photometric data from a Hubble Space Telescope Multi-Cycle Treasury program: Panchromatic Hubble Andromeda Treasury (PHAT). The PHAT data set includes deep photometry in six filters: two in the ultraviolet, two in the optical, and two in the near infrared. The carbon stars appear to be in the asymptotic giant branch stage of their evolution as evidenced by the fact that they lie above the tip of the red giant branch and are cleanly separated from normal (i.e., oxygen-rich) giants in color-magnitude diagrams. We study the spatial distribution of carbon stars in M31 and use kinematics to determine whether they belong to M31's thin disk, thick disk, or spheroid. These carbon stars serve as highly visible tracers of the intermediate-mass, intermediate-age stellar population in M31; they are important markers in the study of the star-formation history of the galaxy. This research was part of the SPLASH and PHAT collaboration. We are grateful to the National Science Foundation and NASA for funding support. AN's participation was under the auspices of UCSC's Science Internship Program.

Exploring the Interactions between Land Use, Climate Change and Carbon Cycle using Satellite Measurements

NASA Astrophysics Data System (ADS)

Ray, R. L.; Fares, A.; He, Y.; Awal, R.; Risch, E.

2017-12-01

Most climate change impacts are linked to terrestrial vegetation productivity, carbon stocks and land use change. Changes in land use and climate drive the dynamics of terrestrial carbon cycle. These carbon cycle dynamics operate at different spatial and temporal scales. Quantification of the spatial and temporal variability of carbon flux has been challenging because land-atmosphere-carbon exchange is influenced by many factors, including but not limited to, land use change and climate change and variability. The study of terrestrial carbon cycle, mainly gross primary product (GPP), net ecosystem exchange (NEE), soil organic carbon (SOC) and ecosystem respiration (Re) and their interactions with land use and climate change, are critical to understanding the terrestrial ecosystem. The main objective of this study was to examine the interactions among land use, climate change and terrestrial carbon cycling in the state of Texas using satellite measurements. We studied GPP, NEE, Re and SOC distributions for five selected major land covers and all ten climate zones in Texas using Soil Moisture Active Passive (SMAP) carbon products. SMAP Carbon products (Res=9 km) were compared with observed CO2 flux data measured at EC flux site on Prairie View A&M University Research Farm. Results showed the same land cover in different climate zones has significantly different carbon sequestration potentials. For example, cropland of the humid climate zone has higher (-228 g C/m2) carbon sequestration potentials than the semiarid climate zone (-36 g C/m2). Also, shrub land in the humid zone and in the semiarid zone showed high (-120 g C/m2) and low (-36 g C/m2) potentials of carbon sequestration, respectively, in the state. Overall, the analyses indicate CO2 storage and exchange respond differently to various land covers, and environments due to differences in water availability, root distribution and soil properties.

"Days of future passed" - climate change and carbon cycle history (Jean Baptiste Lamarck Medal Lecture)

NASA Astrophysics Data System (ADS)

Weissert, Helmut

2013-04-01

With the beginning of the fossil fuel age in the 19th century mankind has become an important geological agent on a global scale. For the first time in human history action of man has an impact on global biogeochemical cycles. Increasing CO2 concentrations will result in a perturbation of global carbon cycling coupled with climate change. Investigations of past changes in carbon cycling and in climate will improve our predictions of future climate. Increasing atmospheric CO2 concentrations will drive climate into a mode of operation, which may resemble climate conditions in the deep geological past. Pliocene climate will give insight into 400ppm world with higher global sea level than today. Doubling of pre-industrial atmospheric CO2 levels will shift the climate system into a state resembling greenhouse climate in the Early Cenozoic or even in the Cretaceous. Carbon isotope geochemistry serves as tool for tracing the pathway of the carbon cycle through geological time. Globally registered negative C-isotope anomalies in the C-isotope record are interpreted as signatures of rapid addition (103 to a few 104 years) of CO2 to the ocean-atmosphere system. Positive C-isotope excursions following negative spikes record the slow post-perturbation recovery of the biosphere at time scales of 105 to 106 years. Duration of C-cycle perturbations in earth history cannot be directly compared with rapid perturbation characterizing the Anthropocene. However, the investigation of greenhouse pulses in the geological past provides insight into different climate states, it allows to identify tipping points in past climate systems and it offers the opportunity to learn about response reactions of the biosphere to rapid changes in global carbon cycling. Sudden injection of massive amounts of carbon dioxide into the atmosphere is recorded in C-isotope record of the Early Cretaceous. The Aptian carbon cycle perturbation triggered changes in temperature and in global hydrological cycling. Changes in physical and chemical oceanography are reflected in widespread black shale deposition ("Oceanic Anoxic Event 1a"), in carbonate platform drowning and in biocalcification crises. "Days of future passed" (Moody Blues, 1967) reminds us that the past provides essential information needed for decisions to be made in the interest of mankind's future.

A life-cycle approach to technology, infrastructure, and climate policy decision making: Transitioning to plug-in hybrid electric vehicles and low-carbon electricity

NASA Astrophysics Data System (ADS)

Samaras, Constantine

In order to mitigate the most severe effects of climate change, large global reductions in the current levels of anthropogenic greenhouse gas (GHG) emissions are required in this century to stabilize atmospheric carbon dioxide (CO2) concentrations at less than double pre-industrial levels. The Intergovernmental Panel on Climate Change (IPCC) fourth assessment report states that GHG emissions should be reduced to 50-80% of 2000 levels by 2050 to increase the likelihood of stabilizing atmospheric CO2 concentrations. In order to achieve the large GHG reductions by 2050 recommended by the IPCC, a fundamental shift and evolution will be required in the energy system. Because the electric power and transportation sectors represent the largest GHG emissions sources in the United States, a unique opportunity for coupling these systems via electrified transportation could achieve synergistic environmental (GHG emissions reductions) and energy security (petroleum displacement) benefits. Plug-in hybrid electric vehicles (PHEVs), which use electricity from the grid to power a portion of travel, could play a major role in reducing greenhouse gas emissions from the transport sector. However, this thesis finds that life cycle GHG emissions from PHEVs depend on the electricity source that is used to charge the battery, so meaningful GHG emissions reductions with PHEVs are conditional on low-carbon electricity sources. Power plants and their associated GHGs are long-lived, and this work argues that decisions made regarding new electricity supplies within the next ten years will affect the potential of PHEVs to play a role in a low-carbon future in the coming decades. This thesis investigates the life cycle engineering, economic, and policy decisions involved in transitioning to PHEVs and low-carbon electricity. The government has a vast array of policy options to promote low-carbon technologies, some of which have proven to be more successful than others. This thesis uses life cycle assessment to evaluate options and opportunities for large GHG reductions from plug-in hybrids. After the options and uncertainties are framed, engineering economic analysis is used to evaluate the policy actions required for adoption of PHEVs at scale and the implications for low-carbon electricity investments. A logistic PHEV adoption model is constructed to parameterize implications for low-carbon electricity infrastructure investments and climate policy. This thesis concludes with an examination of what lessons can be learned for climate, innovation, and low-carbon energy policies from the evolution of wind power from an emerging alternative energy technology to a utility-scale power source. Policies to promote PHEVs and other emerging energy technologies can take lessons learned from the successes and challenges of wind power's development to optimize low-carbon energy policy and R&D programs going forward. The need for integrated climate policy, energy policy, sustainability, and urban mobility solutions will accelerate in the next two decades as concerns regarding GHG emissions and petroleum resources continue to be environmental and economic priorities. To assist in informing the discussions on climate policy and low-carbon energy R&D, this research and its methods will provide stakeholders in government and industry with plug-in hybrid and energy policy choices based on life cycle assessment, engineering economics, and systems analysis.

Responses of the terrestrial carbon cycle to drought: modeling sensitivities of the interactive nitrogen and dynamic vegetation

NASA Astrophysics Data System (ADS)

Jia, B.; Wang, Y.; Xie, Z.

2016-12-01

Drought can trigger both immediate and time-lagged responses of terrestrial ecosystems and even cause sizeable positive feedbacks to climate warming. In this study, the influences of interactive nitrogen (N) and dynamic vegetation (DV) on the response of the carbon cycle in terrestrial ecosystems of China to drought were investigated using the Community Land Model version 4.5 (CLM4.5). Model simulations from three configurations of CLM4.5 (C, carbon cycle only; CN, dynamic carbon and nitrogen cycle; CNDV, dynamic carbon and nitrogen cycle as well as dynamic vegetation) between 1961 and 2010 showed that the incorporation of a prognostic N cycle and DV into CLM4.5 reduce the predicted annual means and inter-annual variability of predicted gross primary production (GPP) and net ecosystem production (NEP), except for a slight increase in NEP for CNDV compared to CN. These model improvements resulted in better agreement with observations (7.0 PgC yr-1) of annual GPP over the terrestrial ecosystems in China for CLM45-CN (7.5 PgC yr-1) and CLM45-CNDV (7.3 PgC yr-1) than for CLM45-C (10.9 PgC yr-1). Compared to the CLM45-C, the carbon-nitrogen coupling strengthened the predicted response of GPP to drought, resulting in a higher correlation with the standardized precipitation index (SPI; rC = 0.62, rCN = 0.67), but led to a weaker sensitivity of NEP to SPI (rC = 0.51, rCN = 0.45). The CLM45-CNDV had the longest lagged responses of GPP to drought among the three configurations. These results enhance our understanding of the response of the terrestrial carbon cycle to drought.

Simulating carbon flows in Amazonian rainforests: how intensive C-cycle data can help to reduce vegetation model uncertainty

NASA Astrophysics Data System (ADS)

Galbraith, D.; Levine, N. M.; Christoffersen, B. O.; Imbuzeiro, H. A.; Powell, T.; Costa, M. H.; Saleska, S. R.; Moorcroft, P. R.; Malhi, Y.

2014-12-01

The mathematical codes embedded within different vegetation models ultimately represent alternative hypotheses of biosphere functioning. While formulations for some processes (e.g. leaf-level photosynthesis) are often shared across vegetation models, other processes (e.g. carbon allocation) are much more variable in their representation across models. This creates the opportunity for equifinality - models can simulate similar values of key metrics such as NPP or biomass through very different underlying causal pathways. Intensive carbon cycle measurements allow for quantification of a comprehensive suite of carbon fluxes such as the productivity and respiration of leaves, roots and wood, allowing for in-depth assessment of carbon flows within ecosystems. Thus, they provide important information on poorly-constrained C-cycle processes such as allocation. We conducted an in-depth evaluation of the ability of four commonly used dynamic global vegetation models (CLM, ED2, IBIS, JULES) to simulate carbon cycle processes at ten lowland Amazonian rainforest sites where individual C-cycle components have been measured. The rigorous model-data comparison procedure allowed identification of biases which were specific to different models, providing clear avenues for model improvement and allowing determination of internal C-cycling pathways that were better supported by data. Furthermore, the intensive C-cycle data allowed for explicit testing of the validity of a number of assumptions made by specific models in the simulation of carbon allocation and plant respiration. For example, the ED2 model assumes that maintenance respiration of stems is negligible while JULES assumes equivalent allocation of NPP to fine roots and leaves. We argue that field studies focusing on simultaneous measurement of a large number of component fluxes are fundamentally important for reducing uncertainty in vegetation model simulations.

Simulated Carbon Cycling in a Model Microbial Mat.

NASA Astrophysics Data System (ADS)

Decker, K. L.; Potter, C. S.

2006-12-01

We present here the novel addition of detailed organic carbon cycling to our model of a hypersaline microbial mat ecosystem. This ecosystem model, MBGC (Microbial BioGeoChemistry), simulates carbon fixation through oxygenic and anoxygenic photosynthesis, and the release of C and electrons for microbial heterotrophs via cyanobacterial exudates and also via a pool of dead cells. Previously in MBGC, the organic portion of the carbon cycle was simplified into a black-box rate of accumulation of simple and complex organic compounds based on photosynthesis and mortality rates. We will discuss the novel inclusion of fermentation as a source of carbon and electrons for use in methanogenesis and sulfate reduction, and the influence of photorespiration on labile carbon exudation rates in cyanobacteria. We will also discuss the modeling of decomposition of dead cells and the ultimate release of inorganic carbon. The detailed modeling of organic carbon cycling is important to the accurate representation of inorganic carbon flux through the mat, as well as to accurate representation of growth models of the heterotrophs under different environmental conditions. Because the model ecosystem is an analog of ancient microbial mats that had huge impacts on the atmosphere of early earth, this MBGC can be useful as a biological component to either early earth models or models of other planets that potentially harbor life.

Net community production and calcification from 7 years of NOAA Station Papa Mooring measurements

NASA Astrophysics Data System (ADS)

Fassbender, Andrea J.; Sabine, Christopher L.; Cronin, Meghan F.

2016-02-01

Seven years of near-continuous observations from the Ocean Station Papa (OSP) surface mooring were used to evaluate drivers of marine carbon cycling in the eastern subarctic Pacific. Processes contributing to mixed layer carbon inventory changes throughout each deployment year were quantitatively assessed using a time-dependent mass balance approach in which total alkalinity and dissolved inorganic carbon were used as tracers. By using two mixed layer carbon tracers, it was possible to isolate the influences of net community production (NCP) and calcification. Our results indicate that the annual NCP at OSP is 2 ± 1 mol C m-2 yr-1 and the annual calcification is 0.3 ± 0.3 mol C m-2 yr-1. Piecing together evidence for potentially significant dissolved organic carbon cycling in this region, we estimate a particulate inorganic carbon to particulate organic carbon ratio between 0.15 and 0.25. This is at least double the global average, adding to the growing evidence that calcifying organisms play an important role in carbon export at this location. These results, coupled with significant seasonality in the NCP, suggest that carbon cycling near OSP may be more complex than previously thought and highlight the importance of continuous observations for robust assessments of biogeochemical cycling.

New Insights into Early Cenozoic Carbon Cycling: Continental Ecosystem Response to Orbital Forcing in the Lacustrine Green River Formation (Western US) at the Conclusion of the Early Eocene Climatic Optimum

NASA Astrophysics Data System (ADS)

Musher, D.; Grogan, D. S.; Whiteside, J. H.

2010-12-01

A series of extreme warming events, known as hyperthermals, interrupted the equable climate conditions predominant during the early Cenozoic hothouse. In marine sediments, these hyperthermals are marked by prominent negative carbon isotope excursions, indicative of dramatic and abrupt changes in the global exogenic carbon pool, as well as carbonate dissolution horizons and benthic foraminiferal extinctions. Hyperthermals are well documented in the marine record, but it is less clear how patterns of global carbon cycling manifested in early Cenozoic terrestrial environments, although some studies have documented amplified excursions relative to that of the marine record. The lacustrine Eocene Green River Formation of Utah is an excellent system for studying the continental environmental context of global carbon cycle dynamics during this time. These sediments span a ~15 Myr time interval, including the entire Early Eocene Climatic Optimum (EECO) and the transition to the long-term Cenozoic cooling trend. To investigate the relationship between the continental carbon record and global carbon cycling, climate, and orbital forcing, we studied a detailed section from the P-4 core drilled in the Uinta Basin bracketing the famous “Mahogany Bed”, a petroliferous layer of oil shale recording a period of enhanced productivity and carbon burial near the end of the EECO. Our carbon isotope measurements of high molecular weight n-alkanes across this boundary suggest a stable global carbon cycle and climate regime persisting ~400 kyr at the terminal EECO. Frequency spectra of published oil yield and gamma ray data from this section reveal concentrated power at Milankovitch frequencies, permitting the assembly of a robust age model. In concert with radioisotopic age control, our orbital chronology allows for comparison of our carbon cycle record to early Eocene astronomical solutions. We show that the Mahogany Bed corresponds to strong minima in short and long eccentricity and a node in obliquity. We hypothesize that sustained low amplitude variability in obliquity combined with low eccentricity favored further attenuation of mild seasonal variability in an already equable continental environmental regime. These climate conditions are consistent with a highly productive lake scenario and maxima in covarying depth rank, oil yield, and total organic carbon coincident with the Mahogany Bed. Current thought posits that certain orbital configurations, including minima in short and long eccentricity, modulate the timing, and possibly the severity, of early Eocene hyperthermals identified in oceanic sediments. Our findings show that similar Milankovitch forcing elicited dramatic changes in continental carbon cycling during the early Cenozoic, possibly independently of the marine world and without the hallmark carbon isotope signature characteristic of hyperthermals. This highlights a potential difference in ecosystem sensitivity between the terrestrial and marine realm during hothouse climate regimes, as well as the need to constrain and characterize multiple modes of carbon cycle instability in early Cenozoic continental environments.

The electrochemical exploration of double carbon-wrapped Na3V2(PO4)3: Towards long-time cycling and superior rate sodium-ion battery cathode

NASA Astrophysics Data System (ADS)

Li, Sijie; Ge, Peng; Zhang, Chenyang; Sun, Wei; Hou, Hongshuai; Ji, Xiaobo

2017-10-01

Na3V2(PO4)3 (NVP) is a very promising cathode material in sodium ion battery for rapidly emerging large-scale energy storage with its classical 3D NASCION structure. However, the cycling life and rate performances are restricted its low electronic conductivity. To overcome these, the double carbon-wrapped Na3V2(PO4)3 composite is firstly designed through rheological phase approach, delivering enhanced electrochemical properties. The unique double carbon layers are composed of uniform amorphous carbons as protecting framework for stabilizing the structure, as well as the graphitized carbon sheets playing the role of conductive network for better electronic conductivity. This double carbon-wrapped Na3V2(PO4)3 composite exhibits a high reversible capacity of 99.8 mAh g-1 over 500 cycles at 1 C (110 mA g-1), yielding the coulombic efficiency of ∼99.8%. Meanwhile, it displays an initial capacity of 73 mAh g-1 at 100 C and remains 55 mAh g-1 at an ultra-rate of 200 C. Even after cycling at 200 C over 12 000 cycles, the Na+-storage capacity of 40 mAh g-1 with a retention of 72.7% is still obtained, highlighting its excellent long cycling life and remarkable rate performances.

40 CFR Table 13 to Subpart G of... - Wastewater-Monitoring Requirements for Control Devices

Code of Federal Regulations, 2014 CFR

2014-07-01

.... Carbon adsorber (regenerative) Integrating regeneration stream flow monitoring device having an accuracy of ±10 percent, and Total regeneration stream mass or volumetric flow during carbon bed regeneration cycle(s) For each regeneration cycle, record the total regeneration stream mass or volumetric flow...

40 CFR Table 13 to Subpart G of... - Wastewater-Monitoring Requirements for Control Devices

Code of Federal Regulations, 2012 CFR

2012-07-01

.... Carbon adsorber (regenerative) Integrating regeneration stream flow monitoring device having an accuracy of ±10 percent, and Total regeneration stream mass or volumetric flow during carbon bed regeneration cycle(s) For each regeneration cycle, record the total regeneration stream mass or volumetric flow...

40 CFR Table 13 to Subpart G of... - Wastewater-Monitoring Requirements for Control Devices

Code of Federal Regulations, 2013 CFR

2013-07-01

.... Carbon adsorber (regenerative) Integrating regeneration stream flow monitoring device having an accuracy of ±10 percent, and Total regeneration stream mass or volumetric flow during carbon bed regeneration cycle(s) For each regeneration cycle, record the total regeneration stream mass or volumetric flow...

40 CFR Table 13 to Subpart G of... - Wastewater-Monitoring Requirements for Control Devices

Code of Federal Regulations, 2011 CFR

2011-07-01

.... Carbon adsorber (regenerative) Integrating regeneration stream flow monitoring device having an accuracy of ±10 percent, and Total regeneration stream mass or volumetric flow during carbon bed regeneration cycle(s) For each regeneration cycle, record the total regeneration stream mass or volumetric flow...

40 CFR Table 13 to Subpart G of... - Wastewater-Monitoring Requirements for Control Devices

Code of Federal Regulations, 2010 CFR

2010-07-01

.... Carbon adsorber (regenerative) Integrating regeneration stream flow monitoring device having an accuracy of ±10 percent, and Total regeneration stream mass or volumetric flow during carbon bed regeneration cycle(s) For each regeneration cycle, record the total regeneration stream mass or volumetric flow...

Deconvolving the Fate of Carbon in Coastal Sediments

NASA Astrophysics Data System (ADS)

Van der Voort, Tessa S.; Mannu, Utsav; Blattmann, Thomas M.; Bao, Rui; Zhao, Meixun; Eglinton, Timothy I.

2018-05-01

Coastal oceans play a crucial role in the global carbon cycle, and are increasingly affected by anthropogenic forcing. Understanding carbon cycling in coastal environments is hindered by convoluted sources and myriad processes that vary over a range of spatial and temporal scales. In this study, we deconvolve the complex mosaic of organic carbon manifested in Chinese Marginal Sea (CMS) sediments using a novel numerical clustering algorithm based on 14C and total OC content. Results reveal five regions that encompass geographically distinct depositional settings. Complementary statistical analyses reveal contrasting region-dependent controls on carbon dynamics and composition. Overall, clustering is shown to be highly effective in demarcating areas of distinct organic facies by disentangling intertwined organic geochemical patterns resulting from superimposed effects of OC provenance, reworking and deposition on a shelf region exhibiting pronounced spatial heterogeneity. This information will aid in constraining region-specific budgets of carbon burial and carbon cycle processes.

Variation in the carbon cycle of the Sevastopol Bay (Black Sea)

NASA Astrophysics Data System (ADS)

Orekhova, N. A.; Konovalov, S. K.

2018-01-01

Continuous increase in CO2 inventory in the ocean results in dramatic changes in marine biogeochemistry, e.g. acidification. That is why temporal and spatial variabilities in atmospheric pCO2 and dissolved inorganic carbon, including CO2, pH and alkalinity in water, as well as organic and inorganic carbon in bottom sediments have to be studied together making possible to resolve the key features of the carbon cycle transformation. A 30% increase of pCO2 in the Sevastopol Bay for 2008 - 2016 evidences changes in the DIC components ratios and a significant decrease in the ability to absorb atmospheric CO2 by surface waters. High organic carbon content in the bottom sediments and predominance of organic carbon production in the biological pump at inner parts of the bay reveal ongoing transformation of the carbon cycle. This has negative consequences for recreation, social and economic potentials of the Sevastopol region.

Regional carbon cycle responses to 25 years of variation in climate and disturbance in the US Pacific Northwest

Treesearch

David P. Turner; William D. Ritts; Robert E. Kennedy; Andrew N. Gray; Zhiqiang Yang

2016-01-01

Variation in climate, disturbance regime, and forest management strongly influence terrestrial carbon sources and sinks. Spatially distributed, process-based, carbon cycle simulation models provide a means to integrate information on these various influences to estimate carbon pools and flux over large domains. Here we apply the Biome-BGC model over the four-state...

Simulating the impacts of disturbances on forest carbon cycling in North America: processes, data, models, and challenges

Treesearch

Shuguang Liu; Ben Bond-Lamberty; Jeffrey A. Hicke; Rodrigo Vargas; Shuqing Zhao; Jing Chen; Steven L. Edburg; Yueming Hu; Jinxun Liu; A. David McGuire; Jingfeng Xiao; Robert Keane; Wenping Yuan; Jianwu Tang; Yiqi Luo; Christopher Potter; Jennifer Oeding

2011-01-01

Forest disturbances greatly alter the carbon cycle at various spatial and temporal scales. It is critical to understand disturbance regimes and their impacts to better quantify regional and global carbon dynamics. This review of the status and major challenges in representing the impacts of disturbances in modeling the carbon dynamics across North America revealed some...

The role of harvest residue in rotation cycle carbon balance in loblolly pine plantations

Treesearch

Asko Noormets; Steve G. Mcnulty; Jean-Christophe Domec; Michael Gavazzi; Ge Sun; John S. King

2012-01-01

Timber harvests remove a significant portion of ecosystem carbon. While some of the wood products moved off-site may last past the harvest cycle of the particular forest crop, the effect of the episodic disturbances on long-term on-site carbon sequestration is unclear. The current study presents a 25 year carbon budget estimate for a typical commercial loblolly pine...

Interannual variability of terrestrial NEP and its attributions to carbon uptake amplitude and period

NASA Astrophysics Data System (ADS)

Niu, S.

2015-12-01

Earth system exhibits strong interannual variability (IAV) in the global carbon cycle as reflected in the year-to-year anomalies of the atmospheric CO2 concentration. Although various analyses suggested that land ecosystems contribute mostly to the IAV of atmospheric CO2 concentration, processes leading to the IAV in the terrestrial carbon (C) cycle are far from clear and hinder our effort in predicting the IAV of global C cycle. Previous studies on IAV of global C cycle have focused on the regulation of climatic variables in tropical or semiarid areas, but generated inconsistent conclusions. Using long-term eddy-flux measurements of net ecosystem production (NEP), atmospheric CO2 inversion NEP, and the MODIS-derived gross primary production (GPP), we demonstrate that seasonal carbon uptake amplitude (CUA) and period (CUP) are two key processes that control the IAV in the terrestrial C cycle. The two processes together explain 78% of the variations in the IAV in eddy covariance NEP, 70% in global atmospheric inversed NEP, and 53% in the IAV of GPP. Moreover, the three lines of evidence consistently show that variability in CUA is much more important than that of CUP in determining the variation of NEP at most eddy-flux sites, and most grids of global NEP and GPP. Our results suggest that the maximum carbon uptake potential in the peak-growing season is a determinant process of global C cycle internnual variability and carbon uptake period may play less important role than previous expectations. This study uncovers the most parsimonious, proximate processes underlying the IAV in global C cycle of the Earth system. Future research is needed to identify how climate factors affect the IAV in terrestrial C cycle through their influence on CUA and CUP.

Carbon Quantum Dots and Their Derivative 3D Porous Carbon Frameworks for Sodium-Ion Batteries with Ultralong Cycle Life.

PubMed

Hou, Hongshuai; Banks, Craig E; Jing, Mingjun; Zhang, Yan; Ji, Xiaobo

2015-12-16

A new methodology for the synthesis of carbon quantum dots (CQDs) for large production is proposed. The as-obtained CQDs can be transformed into 3D porous carbon frameworks exhibiting superb sodium storage properties with ultralong cycle life and ultrahigh rate capability, comparable to state-of-the-art carbon anode materials for sodium-ion batteries. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Long-term climate change and the geochemical cycle of carbon

NASA Technical Reports Server (NTRS)

Marshall, Hal G.; Walker, James C. G.; Kuhn, William R.

1988-01-01

The response of the coupled climate-geochemical system to changes in paleography is examined in terms of the biogeochemical carbon cycle. The simple, zonally averaged energy balance climate model combined with a geochemical carbon cycle model, which was developed to study climate changes, is described. The effects of latitudinal distributions of the continents on the carbon cycle are investigated, and the global silicate weathering rate as a function of latitude is measured. It is observed that a concentration of land area at high altitudes results in a high CO2 partial pressure and a high global average temperature, and for land at low latitudes a cold globe and ice are detected. It is noted that the CO2 greenhouse feedback effect is potentially strong and has a stabilizing effect on the climate system.

Crosslinked Carbon Nanotubes/Polyaniline Composites as a Pseudocapacitive Material with High Cycling Stability

PubMed Central

Liu, Dong; Wang, Xue; Deng, Jinxing; Zhou, Chenglong; Guo, Jinshan; Liu, Peng

2015-01-01

The poor cycling stability of polyaniline (PANI) limits its practical application as a pseudocapacitive material due to the volume change during the charge-discharge procedure. Herein, crosslinked carbon nanotubes/polyaniline (C-CNTs/PANI) composites had been designed by the in situ chemical oxidative polymerization of aniline in the presence of crosslinked carbon nanotubes (C-CNTs), which were obtained by coupling of the functionalized carbon nanotubes with 1,4-benzoquinone. The composite showed a specific capacitance of 294 F/g at the scan rate of 10 mV/s, and could retain 95% of its initial specific capacitance after 1000 CV cycles. Such high electrochemical cycling stability resulting from the crosslinked skeleton of the C-CNTs makes them potential electrode materials for a supercapacitor. PMID:28347050

Porous carbon with a large surface area and an ultrahigh carbon purity via templating carbonization coupling with KOH activation as excellent supercapacitor electrode materials

NASA Astrophysics Data System (ADS)

Sun, Fei; Gao, Jihui; Liu, Xin; Pi, Xinxin; Yang, Yuqi; Wu, Shaohua

2016-11-01

Large surface area and good structural stability, for porous carbons, are two crucial requirements to enable the constructed supercapacitors with high capacitance and long cycling lifespan. Herein, we successfully prepare porous carbon with a large surface area (3175 m2 g-1) and an ultrahigh carbon purity (carbon atom ratio of 98.25%) via templating carbonization coupling with KOH activation. As-synthesized MTC-KOH exhibits excellent performances as supercapacitor electrode materials in terms of high specific capacitance and ultrahigh cycling stability. In a three electrode system, MTC-KOH delivers a high capacitance of 275 F g-1 at 0.5 A g-1 and still 120 F g-1 at a high rate of 30 A g-1. There is almost no capacitance decay even after 10,000 cycles, demonstrating outstanding cycling stability. In comparison, pre-activated MTC with a hierarchical pore structure shows a better rate capability than microporous MTC-KOH. Moreover, the constructed symmetric supercapacitor using MTC-KOH can achieve high energy densities of 8.68 Wh kg-1 and 4.03 Wh kg-1 with the corresponding power densities of 108 W kg-1 and 6.49 kW kg-1, respectively. Our work provides a simple design strategy to prepare highly porous carbons with high carbon purity for supercapacitors application.

Not all droughts are created equal: the impacts of interannual drought pattern and magnitude on grassland carbon cycling.

PubMed

Hoover, David L; Rogers, Brendan M

2016-05-01

Climate extremes, such as drought, may have immediate and potentially prolonged effects on carbon cycling. Grasslands store approximately one-third of all terrestrial carbon and may become carbon sources during droughts. However, the magnitude and duration of drought-induced disruptions to the carbon cycle, as well as the mechanisms responsible, remain poorly understood. Over the next century, global climate models predict an increase in two types of drought: chronic but subtle 'press-droughts', and shorter term but extreme 'pulse-droughts'. Much of our current understanding of the ecological impacts of drought comes from experimental rainfall manipulations. These studies have been highly valuable, but are often short term and rarely quantify carbon feedbacks. To address this knowledge gap, we used the Community Land Model 4.0 to examine the individual and interactive effects of pulse- and press-droughts on carbon cycling in a mesic grassland of the US Great Plains. A series of modeling experiments were imposed by varying drought magnitude (precipitation amount) and interannual pattern (press- vs. pulse-droughts) to examine the effects on carbon storage and cycling at annual to century timescales. We present three main findings. First, a single-year pulse-drought had immediate and prolonged effects on carbon storage due to differential sensitivities of ecosystem respiration and gross primary production. Second, short-term pulse-droughts caused greater carbon loss than chronic press-droughts when total precipitation reductions over a 20-year period were equivalent. Third, combining pulse- and press-droughts had intermediate effects on carbon loss compared to the independent drought types, except at high drought levels. Overall, these results suggest that interannual drought pattern may be as important for carbon dynamics as drought magnitude and that extreme droughts may have long-lasting carbon feedbacks in grassland ecosystems. Published 2015. This article is a U.S. Government work and is in the public domain in the USA.

Interlinkages between Carbon and Water Residence Times in Peat

NASA Astrophysics Data System (ADS)

Visser, A.; Wilson, R.; Sebestyen, S.; Griffiths, N.; Chanton, J.; Veale, N.; McFarlane, K. J.; Kolka, R. K.; Guilderson, T.

2016-12-01

Peatlands play an important role in the terrestrial carbon cycle. Understanding their response to climate change is crucial to predict their role as carbon sink or source of methane and carbon dioxide to the atmosphere. The hydrology of the peatland plays a crucial role, providing anoxic conditions for peat accumulation and advective transport of nutrients and dissolved organic carbon (DOC) to methanogens at depth. The interlinkages between the hydrology and carbon-cycling at the S1 bog at the Marcell Experimental Forest were investigated as part of the SPRUCE experiment, using a combination of isotopic techniques characterizing the carbon and water ages to assess the role of advective transport in the peat pore water. Tritium and tritiogenic helium concentrations constrain the age of the pore water to less than 10 years, although gas exchange with the atmosphere complicates direct use of 3H/3He dating methods. The pore water ages further constrain the interpretation of the peat, DOC and DIC ages. While carbon-14 values of solid peat decrease from 0‰ at the surface to -550‰ (corresponding to carbon-14 ages of 8 ka) at 2m depth, the DOC and DIC shift from +50‰ to -50‰ at depth. Knowing that the advective transport time of pore water is negligible on this time scale, the shift in carbon-14 of DOC must result from peat decomposition at depth, rather than in situ aging of DOC. Combined with the DOC concentration data, the carbon-cycling rates at the SPRUCE experiment are further constrained. The integrated application of isotopes in the carbon and water cycle emphasizes the importance of understanding peatland hydrology for understanding carbon-cycle dynamics. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. LLNL-ABS-675107

Effects of Light Stress on Extracellular Cycling in a Cyanobacterial Biofilm Community

NASA Astrophysics Data System (ADS)

Stuart, R.; Mayali, X.; Pett-Ridge, J.; Weber, P. K.; Thelen, M.; Bebout, B.; Lipton, M. S.

2015-12-01

Cyanobacterial carbon excretion is crucial to carbon cycling in many microbial communities, but the nature and bioavailability of the carbon excreted is dependent on physiological function, which is often unknown. Cyanobacteria are the dominant primary producers in hypersaline mats and there is large reservoir of carbon in the extracellular matrix, but the nature and flux is understudied. In a previous study, we examined the macromolecular composition of the matrix of microbial mats from Elkhorn Slough in Monterey Bay, California and a unicyanobacterial culture, ESFC-1, isolated from the those mats, and found evidence for cyanobacterial degradation and re-uptake of extracellular organic matter. In this work, we further explore mechanisms of this degradation and re-uptake by examining effects of light using a combination of high-resolution imaging mass spectrometry (NanoSIMS) and metaproteomics of extracellular proteins. Based on these findings, we propose that mat Cyanobacteria store and recycle organic material from the mat extracellular matrix. Cyanobacteria can account for 70-90% of the biomass in the upper phototrophic layer of the mats, so their re-uptake of organic carbon and nitrogen has the potential to re-define organic matter availability in these systems. This work has implications for cyanobacterial adaptation to dynamic environments like microbial mats, where uptake of carbon and nitrogen in variable forms may be necessary to persist. This research was supported by the U.S. Department of Energy Office of Science, Office of Biological and Environmental Research Genomic Science program under FWP SCW1039. Work at LLNL was performed under the auspices of the U.S. Department of Energy under Contract DE-AC52-07NA27344.

The effects of land use on fluvial sediment chemistry for the conterminous U.S. - Results from the first cycle of the NAWQA Program: Trace and major elements, phosphorus, carbon, and sulfur

USGS Publications Warehouse

Horowitz, A.J.; Stephens, V.C.

2008-01-01

In 1991, the U.S. Geological Survey (USGS) began the first cycle of its National Water Quality Assessment (NAWQA) Program. The Program encompassed 51 river basins that collectively accounted for more than 70% of the total water use (excluding power generation), and 50% of the drinking water supply in the U.S. The basins represented a variety of hydrologic settings, rock types (geology), land-use categories, and population densities. One aspect of the first cycle included bed sediment sampling; sites were chosen to represent baseline and important land-use categories (e.g., agriculture, urban) in each basin. In total, over 1200 bed sediment samples were collected. All samples were size-limited (< 63????m) to facilitate spatial and/or temporal comparisons, and subsequently analyzed for a variety of chemical constituents including major (e.g., Fe, Al,) and trace elements (e.g., Cu, Zn, Cd), nutrients (e.g., P), and carbon. The analyses yielded total (??? 95% of the concentrations present), rather than total-recoverable chemical data. Land-use percentages, upstream underlying geology, and population density were determined for each site and evaluated to asses their relative influence on sediment chemistry. Baseline concentrations for the entire U.S. also were generated from a subset of all the samples, and are based on material collected from low population (??? 27??p km- 2) density, low percent urban (??? 5%), agricultural or undeveloped areas. The NAWQA baseline values are similar to those found in other national and global datasets. Further, it appears that upstream/underlying rock type has only a limited effect (mostly major elements) on sediment chemistry. The only land-use category that appears to substantially affect sediment chemistry is percent urban, and this result is mirrored by population density; in fact, the latter appears more consistent than the former.

Carbon cycling at the tipping point: Does ecosystem structure predict resistance to disturbance?

NASA Astrophysics Data System (ADS)

Gough, C. M.; Bond-Lamberty, B. P.; Stuart-Haentjens, E.; Atkins, J.; Haber, L.; Fahey, R. T.

2017-12-01

Ecosystems worldwide are subjected to disturbances that reshape their physical and biological structure and modify biogeochemical processes, including carbon storage and cycling rates. Disturbances, including those from insect pests, pathogens, and extreme weather, span a continuum of severity and, accordingly, may have different effects on carbon cycling processes. Some ecosystems resist biogeochemical changes following disturbance, until a critical threshold of severity is exceeded. The ecosystem properties underlying such functional resistance, and signifying when a tipping point will occur, however, are almost entirely unknown. Here, we present observational and experimental results from forests in the Great Lakes region, showing ecosystem structure is closely coupled with carbon cycling responses to disturbance, with shifts in structure predicting thresholds of and, in some cases, increases in carbon storage. We find, among forests in the region, that carbon storage regularly exhibits a non-linear threshold response to increasing disturbance levels, but the severity at which a threshold is reached varies among disturbed forests. More biologically and structurally complex forest ecosystems sometimes exhibit greater functional resistance than simpler forests, and consequently may have a higher disturbance severity threshold. Counter to model predictions but consistent with some theoretical frameworks, empirical data show moderate levels of disturbance may increase ecosystem complexity to a point, thereby increasing rates of carbon storage. Disturbances that increase complexity therefore may stimulate carbon storage, while severe disturbances at or beyond thresholds may simplify structure, leading to carbon storage declines. We conclude that ecosystem structural attributes are closely coupled with biogeochemical thresholds across disturbance severity gradients, suggesting that improved predictions of disturbance-related changes in the carbon cycle require better representation of ecosystem structure in models.

Sedimentary evidence for enhanced hydrological cycling in response to rapid carbon release during the early Toarcian oceanic anoxic event

NASA Astrophysics Data System (ADS)

Izumi, Kentaro; Kemp, David B.; Itamiya, Shoma; Inui, Mutsuko

2018-01-01

A pronounced excursion in the carbon-isotope composition of biospheric carbon and coeval seawater warming during the early Toarcian (∼183 Ma) has been linked to the large-scale transfer of 12C-enriched carbon to the oceans and atmosphere. A European bias in the distribution of available data means that the precise pattern, tempo and global expression of this carbon cycle perturbation, and the associated environmental responses, remain uncertain. Here, we present a new cm-scale terrestrial-dominated carbon-isotope record through an expanded lower Toarcian section from Japan that displays a negative excursion pattern similar to marine and terrestrial carbon-isotope records documented from Europe. These new data suggest that 12C-enriched carbon was added to the biosphere in at least one rapid, millennial-scale pulse. Sedimentological analysis indicates a close association between the carbon-isotope excursion and high-energy sediment transport and enhanced fluvial discharge. Together, these data support the hypothesis that a sudden strengthening of the global hydrological cycle occurred in direct and immediate response to rapid carbon release and atmospheric warming.

Climate warming and the carbon cycle in the permafrost zone of the former Soviet Union

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

Kolchugina, T.P.; Vinson, T.S.

1993-01-01

The continuous permafrost zone of the former Soviet Union occupies 5% of the land surface area of the earth and stores a significant amount of carbon. Climate warming could disrupt the balance between carbon (C) accumulation and decomposition processes within the permafrost zone. Increased temperatures may accelerate the rate of organic matter decomposition. At the same time, the productivity of vegetation may increase in response to warming. To assess the future carbon cycle within the permafrost zone under a climate-warming scenario, it is necessary to quantify present carbon pools and fluxes. The present carbon cycle was assessed on the basismore » of an ecosystem/ecoregion approach. Under the present climate, the phytomass carbon pool was estimated at 17.0 Giga tons. The mortmass (coarse woody debris) carbon pool was estimated at 16.1 Giga tons. The soil carbon pool, including peatlands, was 139.4 Giga tons. The present rate of carbon turnover was 1.6 Giga tons/yr. (Copyright (c) 1993 by John Wiley and Sons, Ltd.)« less

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.

Future Projections and Consequences of the Changing North American Carbon Cycle

NASA Astrophysics Data System (ADS)

Huntzinger, D. N.; Cooley, S. R.; Moore, D. J.

2017-12-01

The rise of atmospheric carbon dioxide (CO2), primarily due to human-caused fossil fuel emissions and land-use change, has been dampened by carbon uptake by the oceans and terrestrial biosphere. Nevertheless, today's atmospheric CO2 levels are higher than at any time in the past 800,000 years. Over the past decade, there has been considerable effort to understand how carbon cycle changes interact with, and influence, atmospheric CO2 concentrations and thus climate. Here, we summarize the key findings related to projected changes to the North American carbon cycle and the consequences of these changes as reported in Chapters 17 and 19 of the 2nd State of the Carbon Cycle Report (SOCCR-2). In terrestrial ecosystems, increased atmospheric CO2 causes enhanced photosynthesis, plant growth, and water-use efficiency. Together, these may lead to changes in vegetation composition, carbon storage, hydrology and biogeochemical cycling. In the ocean, increased uptake of atmospheric CO2 causes ocean acidification, which leads to changes in reproduction, survival, and growth of many marine species. These direct physiological responses to acidification are likely to have indirect ecosystem-scale consequences that we are just beginning to understand. In all environments, the effects of rising CO2 also interact with other global changes. For example, nutrient availability can set limits on growth and a warming climate alters carbon uptake depending on a number of other factors. As a result, there is low confidence in the future evolution of the North American carbon cycle. For example, models project that terrestrial ecosystems could continue to be a net sink (of up to 1.19 PgC yr-1) or switch to a net source of carbon to the atmosphere (of up to 0.60 PgC yr-1) by the end of the century under business-as-usual emission scenarios. And, while North American coastal areas have historically been a sink of carbon (e.g., 2.6 to 3.5 PgC since 1995) and are projected to continue to take up carbon into the future, mangroves and wetlands are particularly vulnerable to carbon loss due to sea level rise and other factors. The capacity and longevity of ocean and terrestrial carbon uptake remains uncertain and this uncertainty feeds back to other Earth system processes.

A dual isotope approach to isolate soil carbon pools of different turnover times

DOE PAGES

Torn, M. S.; Kleber, M.; Zavaleta, E. S.; ...

2013-12-10

Soils are globally significant sources and sinks of atmospheric CO 2. Increasing the resolution of soil carbon turnover estimates is important for predicting the response of soil carbon cycling to environmental change. We show that soil carbon turnover times can be more finely resolved using a dual isotope label like the one provided by elevated CO 2 experiments that use fossil CO 2. We modeled each soil physical fraction as two pools with different turnover times using the atmospheric 14C bomb spike in combination with the label in 14C and 13C provided by an elevated CO 2 experiment in amore » California annual grassland. In sandstone and serpentine soils, the light fraction carbon was 21–54% fast cycling with 2–9 yr turnover, and 36–79% slow cycling with turnover slower than 100 yr. This validates model treatment of the light fraction as active and intermediate cycling carbon. The dense, mineral-associated fraction also had a very dynamic component, consisting of ~7% fast-cycling carbon and ~93% very slow cycling carbon. Similarly, half the microbial biomass carbon in the sandstone soil was more than 5 yr old, and 40% of the carbon respired by microbes had been fixed more than 5 yr ago. Resolving each density fraction into two pools revealed that only a small component of total soil carbon is responsible for most CO 2 efflux from these soils. In the sandstone soil, 11% of soil carbon contributes more than 90% of the annual CO 2 efflux. The fact that soil physical fractions, designed to isolate organic material of roughly homogeneous physico-chemical state, contain material of dramatically different turnover times is consistent with recent observations of rapid isotope incorporation into seemingly stable fractions and with emerging evidence for hot spots or micro-site variation of decomposition within the soil matrix. Predictions of soil carbon storage using a turnover time estimated with the assumption of a single pool per density fraction would greatly overestimate the near-term response to changes in productivity or decomposition rates. Therefore, these results suggest a slower initial change in soil carbon storage due to environmental change than has been assumed by simpler (one-pool) mass balance calculations.« less

Carbon Dioxide Effects Research and Assessment Program. The role of tropical forests on the world carbon cycle

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

Brown, S.; Lugo, A. E.; Liegel, B.

1980-08-01

Tropical forests constitute about half of the world's forest and are characterized by rapid rates of organic matter turnover and high storages of organic matter. Tropical forests are considered to be one of the most significant terrestrial elements in the equation that balances the carbon cycle of the world. As discussed in the paper by Tosi, tropical and subtropical latitudes are more complex in terms of climate and vegetation composition than temperate and boreal latitudes. The implications of the complexity of the tropics and the disregard of this complexity by many scientists is made evident in the paper by Brownmore » and Lugo which shows that biomass estimates for tropical ecosystems have been overestimated by at least 100%. The paper by Brown shows that that rates of succession in the tropics are extremely rapid in terms of the ability of moist and wet forests to accumulate organic matter. Yet, in arid tropical Life Zones succession is slow. This leads to the idea that the question of whether tropical forests are sinks or sources of carbon must be analyzed in relation to Life Zones and to intensities of human activity in these Zones. The paper by Lugo presents conceptual models to illustrate this point and the paper by Tosi shows how land uses in the tropics also correspond to Life Zone characteristics. The ultimate significance of land use to the question of the carbon balance in a large region is addressed in the paper by Detwiler and Hall.« less

Complex carbon cycling processes and pathways in a tropical coastal marine environment (Saco do Mamangua, RJ - Brazil)

NASA Astrophysics Data System (ADS)

Giorgioni, M.; Jovane, L.; Millo, C.; Sawakuchi, H. O.; Bertassoli, D. J., Jr.; Gamba Romano, R.; Pellizari, V.; Castillo Franco, D.; Krusche, A. V.

2016-12-01

The Saco do Mamangua is a narrow and elongated gulf located along the southeastern coast of Brazil, in the state of Rio de Janeiro (RJ). It is surrounded by high relieves, which form a peculiar environment called riá, with little river input and limited water exchange with the Atlantic Ocean. These features make the Saco do Mamangua an ideal environment to study sedimentary carbon cycling under well-constrained boundary conditions in order to investigate if tropical coastal environments serve dominantly as potential carbon sinks or sources. In this work we integrate geochemical data from marine sediments and pore waters in the Saco do Mamangua with mapping of benthic microbial communities, in order to unravel the biogeochemical carbon cycling linked to the production of biogenic methane. Our results reveal that carbon cycling occurs in two parallel pathways. The Saco do Mamangua receives organic carbon both by surface runoff and by primary production in the water column. A large part of this organic carbon is buried within the sediment resulting in the production of biogenic methane, which gives rise to methane seepages at the sea floor. These methane seeps sustain methanotrophic microbial communities in the sediment pore water, but also escapes into the atmosphere by ebullition. Consequently, the sediments of Saco do Mamangua acts simultaneously as carbon sink and carbon source. Future work will allow us to accurately quantify the actual carbon fluxes and calculate the net carbon balance in the local environment.

The Contribution of Soils to North America's Current and Future Climate

NASA Astrophysics Data System (ADS)

Mayes, M. A.; Reed, S.; Thornton, P. E.; Lajtha, K.; Bailey, V. L.; Shrestha, G.; Jastrow, J. D.; Torn, M. S.

2015-12-01

This presentation will cover key aspects of the terrestrial soil carbon cycle in North America and the US for the upcoming State of the Carbon Cycle Report (SOCCRII). SOCCRII seeks to summarize how natural processes and human interactions affect the global carbon cycle, how socio-economic trends affect greenhouse gas concentrations in the atmosphere, and how ecosystems are influenced by and respond to greenhouse gas emissions, management decisions, and concomitant climate effects. Here, we will summarize the contemporary understanding of carbon stocks, fluxes, and drivers in the soil ecosystem compartment. We will highlight recent advances in modeling the magnitude of soil carbon stocks and fluxes, as well as the importance of remaining uncertainties in predicting soil carbon cycling and its relationship with climate. Attention will be given to the role of uncertainties in predicting future fluxes from soils, and how those uncertainties vary by region and ecosystem. We will also address how climate feedbacks and management decisions can enhance or minimize future climatic effects based on current understanding and observations, and will highlight select research needs to improve our understanding of the balance of carbon in soils in North America.

Piecing together the fragments: Elucidating edge effects on forest carbon dynamics

NASA Astrophysics Data System (ADS)

Hutyra, L.; Smith, I. A.; Reinmann, A.; Marrs, J.; Thompson, J.

2017-12-01

Forest fragmentation is pervasive throughout the world's forests, impacting growing conditions and carbon dynamics through edge effects that produce gradients in microclimate, biogeochemistry, and stand structure. Despite the majority of the world's forests being <1km from an edge, our understanding of forest carbon dynamics is largely derived from intact forest systems. In the northeastern USA, we find that over 23% of the current forest area is just 30m from an agricultural or developed edge. Edge effects on the carbon cycle vary in their magnitude by biome, but current forest carbon accounting methods and ecosystem models largely do not include edge effects, highlighting an important gap in our understanding of the terrestrial carbon cycle. Characterizing the role of forest fragmentation in regional and global biogeochemical cycles necessitates advancing our understanding of how shifts in microenvironment at the forest edge interact with local prevailing drivers of global change and limitations to microbial activity and forest growth. This study synthesizes the literature related to edge effects and the carbon cycle, considering how fragmentation affects the growing conditions of the world's remaining forests based on risks and opportunities for forests near the edge.

Altered carbon cycling and coupled changes in Early Cretaceous weathering patterns: Evidence from integrated carbon isotope and sandstone records of the western Tethys

NASA Astrophysics Data System (ADS)

Wortmann, Ulrich Georg; Herrle, Jens Olaf; Weissert, Helmut

2004-03-01

In this study we investigate if a major perturbation of the Early Cretaceous carbon cycle was accompanied by altered weathering and erosion rates. The large Aptian carbon isotope anomaly records the response of the biosphere to widespread volcanic activity and probably resulting changes in atmospheric pCO2 levels. Elevated pCO2 levels should also result in an accelerated hydrological cycle and increased silicate weathering, creating a negative feedback loop removing CO2 from the atmosphere. We propose to interpret the widespread occurrence of quartz sandstones in the Tethys-Atlantic seaway as a result of altered weathering and erosion rates in the wake of the Aptian carbon cycle excursion. We challenge the traditional notion that these are 'flysch' deposits associated with Early Cretaceous orogenic movements in the western Tethys. We propose that these sandstones were most likely part of a large conveyor belt system, acting along the Iberian and European margin of the Tethys seaway. Using chemostratigraphic correlations, we show that the activity of this system was only short-lived and coeval with changes in coastal ecology and the Aptian carbon cycle perturbations. We tentatively relate the existence of this system to a transient climate regime, characterized by fluctuating pCO2 levels.

North America's net terrestrial CO2 exchange with the atmosphere 1990-2009

Treesearch

A.W. King; R.J. Andres; K J. Davis; M. Hafer; D.J. Hayes; D.N. Huntzinger; B. de Jong; W.A. Kurz; A.D. McGuire; R. Vargas; Y. Wei; T.O. West; C.W. Woodall

2015-01-01

Scientific understanding of the global carbon cycle is required for developing national and international policy to mitigate fossil fuel CO2 emissions by managing terrestrial carbon uptake. Toward that understanding and as a contribution to the REgional Carbon Cycle Assessment and Processes (RECCAP) project, this paper provides a synthesis of net...

Surface reaction mechanisms during ozone and oxygen plasma assisted atomic layer deposition of aluminum oxide.

PubMed

Rai, Vikrant R; Vandalon, Vincent; Agarwal, Sumit

2010-09-07

We have elucidated the reaction mechanism and the role of the reactive intermediates in the atomic layer deposition (ALD) of aluminum oxide from trimethyl aluminum in conjunction with O(3) and an O(2) plasma. In situ attenuated total reflection Fourier transform infrared spectroscopy data show that both -OH groups and carbonates are formed on the surface during the oxidation cycle. These carbonates, once formed on the surface, are stable to prolonged O(3) exposure in the same cycle. However, in the case of plasma-assisted ALD, the carbonates decompose upon prolonged O(2) plasma exposure via a series reaction kinetics of the type, A (CH(3)) --> B (carbonates) --> C (Al(2)O(3)). The ratio of -OH groups to carbonates on the surface strongly depends on the oxidizing agent, and also the duration of the oxidation cycle in plasma-assisted ALD. However, in both O(3) and O(2) plasma cycles, carbonates are a small fraction of the total number of reactive sites compared to the hydroxyl groups.

A synthesis of the science on forests and carbon for U.S. Forests

Treesearch

Michael G. Ryan; Mark E. Harmon; Richard A. Birdsey; Christian P. Giardina; Linda S. Heath; Richard A. Houghton; Robert B. Jackson; Duncan C. McKinley; James F. Morrison; Brian C. Murray; Diane E. Pataki; Kenneth E. Skog

2010-01-01

Forests play an important role in the U.S. and global carbon cycle, and carbon sequestered by U.S. forest growth and harvested wood products currently offsets 12-19% of U.S. fossil fuel emissions. The cycle of forest growth, death, and regeneration and the use of wood removed from the forest complicate efforts to understand and measure forest carbon pools and flows....

The Seasonal Cycle of Carbon in the Southern Pacific Ocean Observed from Biogeochemical Profiling Floats

NASA Astrophysics Data System (ADS)

Sarmiento, J. L.; Gray, A. R.; Johnson, K. S.; Carter, B.; Riser, S.; Talley, L. D.; Williams, N. L.

2016-02-01

The Southern Ocean is thought to play an important role in the ocean-atmosphere exchange of carbon dioxide and the uptake of anthropogenic carbon dioxide. However, the total number of observations of the carbonate system in this region is small and heavily biased towards the summer. Here we present 1.5 years of biogeochemical measurements, including pH, oxygen, and nitrate, collected by 11 autonomous profiling floats deployed in the Pacific sector of the Southern Ocean in April 2014. These floats sampled a variety of oceanographic regimes ranging from the seasonally ice-covered zone to the subtropical gyre. Using an algorithm trained with bottle measurements, alkalinity is estimated from salinity, temperature, and oxygen and then used together with the measured pH to calculate total carbon dioxide and pCO2 in the upper 1500 dbar. The seasonal cycle in the biogeochemical quantities is examined, and the factors governing pCO2 in the surface waters are analyzed. The mechanisms driving the seasonal cycle of carbon are further investigated by computing budgets of heat, carbon, and nitrogen in the mixed layer. Comparing the different regimes sampled by the floats demonstrates the complex and variable nature of the carbon cycle in the Southern Ocean.

Coupling carbon isotopes with astrochronology and correlation techniques for Late Cretaceous chronostratigraphic refinement and paleoclimate reconstruction

NASA Astrophysics Data System (ADS)

Jones, M. M.; Sageman, B. B.; Meyers, S. R.

2016-12-01

Late Cretaceous carbon isotope ratios (δ13C) recorded in organic matter and marine carbonates preserve an archive of the global carbon cycle in a greenhouse climate state. Due to excellent connectivity among surface carbon reservoirs and the low residence time of carbon in them, excursions in the δ13C that record changes in fluxes serve as widely correlative chronostratigraphic markers. In this study, floating astronomical time scales (ATS) from an organic carbon-rich marine Turonian succession at Demerara Rise (tropical N. Atlantic) are combined with high-resolution δ13C chemostratigraphy to estimate CIE timing and duration for refinement of the geologic time scale. In addition, a Gaussian kernel smoothing technique for objective correlation of astronomically tuned δ13C records is developed. Correlation with three coeval Turonian sections (Western Interior Basin, Texas, & Europe) shows consistency in astronomical and radioisotopic time scale ages for CIEs. In particular, a mid-Turonian sea level fall is demonstrated to be synchronous within 100 ka uncertainty. Spectral analyses of δ13Corg, %TOC, %Carbonate, and C/N time series provide insights into astronomical forcings influencing paleoclimate and paleoceanographic conditions in the tropical proto-North Atlantic upwelling zone. The stable long eccentricity cycle ( 405 ka) is robustly recorded in all geochemical data, and has the highest amplitude in %TOC, %Carbonate, and C/N time series. However, δ13C from Demerara Rise is dominated by a 1 Myr cycle resembling long obliquity, suggesting a dynamic organic carbon reservoir and/or climate feedback originating in high-latitudes was prominent during the Turonian greenhouse carbon cycle. This investigation emphasizes δ13C chemostratigraphy and astrochronology are useful chronostratigraphic methods for importing high-resolution time control into disparate basins to answer questions regarding sea level records, paleoclimate, and mass extinction on a global scale, and at the same time for deciphering the response of the global carbon cycle to astronomical climate forcing.

Orbital-tuning of Marine Cyclic Sediments - Examples from the Neogene and Jurassic

NASA Astrophysics Data System (ADS)

Weedon, G. P.; Hall, I. R.; Wilson, G. S.

2001-12-01

Orbital-tuning of pre-Pleistocene sediments usually involves the use of variations in bulk compositional parameters, such as carbonate contents, rather than the oxygen-isotope time series available from Plio-Pleistocene marine strata. Consequently, ascertaining the relationship between orbital-climatic changes and sediment composition is not straightforward. Tuning is either conducted using a target curve (an orbital solution) for late Cenozoic records, or by using a sine wave with a specified period for earlier records - where a "floating" chronology is generated. Examples of each sort of tuning are discussed here. Drilling during Leg 181 of the Ocean Drilling Program yielded an essentially complete record of sediment-drift accumulation at Site 1123 off New Zealand for the past 20Ma. Dissolution of carbonate in the older part of the section precluded generation of isotopic records for tuning. Instead colour reflectance and magnetic susceptibility were used for tuning between 3 and 15Ma. Additionally, the mean size of sortable silt, a proxy for bottom-water flow speed, was used for orbital-tuning between 12 and 15Ma. Site 1123 possesses an exceptionally well-preserved record of geomagnetic reversals. Thus a preliminary time scale was established using the ages of 60 reversal events between 3 and 15.2Ma (based on Berggren et al., 1995). Since the sediment drift at this site accumulated under the influence of the Pacific deep western boundary current which incorporates circumpolar deep water, the sediment cyclicity is dominated by the 41ka orbital-tilt (obliquity) cycle. Tuning to the tilt cycle required relatively little revision to the ages of the magnetic reversals (maximum 65ka, average 23ka). Evolutionary spectra and band-pass filtering of the tuned reflectance time series reveal a pronounced increase in the amplitude of the stratigraphic record of the obliquity cycle after 7Ma. Eccentricity and precession cycles are evident for short intervals (less than one million years), but they are always subsidiary to the obliquity component - consistent with a high-latitude origin of the variability. The late Jurassic Kimmeridge Clay Formation is the principal oil-source rock in the North Sea Province. It is well-known for cyclic variations in organic-carbon contents linked to alternately oxic and anoxic bottom waters. During the Anatomy of a Source Rock Project, high-resolution (5-20cm) compositional records (e.g. carbonate, total organic carbon, magnetic susceptibility) were obtained from throughout the 550m Formation at the type section in Dorset, England. Spectral analysis indicates regular cyclicity in depth. The regular sedimentary cycles are interpreted as indirect climatic records of the Jurassic obliquity cycle and hence were tuned using a sine wave with a period of 38ka. Evolutionary spectral analysis of the tuned time series reveals small-amplitude 19ka precession cycles, but no evidence for 100 or 400ka orbital-eccentricity cycles. Hence, this record of Late Jurassic climatic variability in Britain implies a high-latitude forcing mechanism. The orbitally-tuned data indicate that ammonite zone durations ranged from 0.36 to 2.3Ma. Accumulation rates (post-compaction) ranged from 20-130m/Ma and organic carbon (post-diagenesis) had a flux of 0.2-2.25g/cm2/ka.

Experimental and theoretical studies on the gas/solid/gas transformation cycle in extraterrestrial environments

NASA Astrophysics Data System (ADS)

Cottin, Hervé; Gazeau, Marie-Claire; Chaquin, Patrick; Raulin, François; Bénilan, Yves

2001-12-01

The ubiquity of molecular material in the universe, from hydrogen to complex organic matter, is the result of intermixed physicochemical processes that have occurred throughout history. In particular, the gas/solid/gas phase transformation cycle plays a key role in chemical evolution of organic matter from the interstellar medium to planetary systems. This paper focuses on two examples that are representative of the diversity of environments where such transformations occur in the Solar System: (1) the photolytic evolution from gaseous to solid material in methane containing planetary atmospheres and (2) the degradation of high molecular weight compounds into gas phase molecules in comets. We are currently developing two programs which couple experimental and theoretical studies. The aim of this research is to provide data necessary to build models in order to better understand (1) the photochemical evolution of Titan's atmosphere, through a laboratory program to determine quantitative spectroscopic data on long carbon chain molecules (polyynes) obtained in the SCOOP program (French acronym for Spectroscopy of Organic Compounds Oriented for Planetology), and (2) the extended sources in comets, through a laboratory program of quantitative studies of photochemical and thermal degradation processes on relevant polymers (e.g., Polyoxymethylene) by the SEMAPhOrE Cometaire program (French acronym for Experimental Simulation and Modeling Applied to Organic Chemistry in Cometary Environment).

Sensitivity of the carbon cycle in the Arctic to climate change

USGS Publications Warehouse

McGuire, A. David; Anderson, Leif G.; Christensen, Torben R.; Dallimore, Scott; Guo, Laodong; Hayes, Daniel J.; Heimann, Martin; Lorenson, T.D.; Macdonald, Robie W.; Roulet, Nigel

2009-01-01

The recent warming in the Arctic is affecting a broad spectrum of physical, ecological, and human/cultural systems that may be irreversible on century time scales and have the potential to cause rapid changes in the earth system. The response of the carbon cycle of the Arctic to changes in climate is a major issue of global concern, yet there has not been a comprehensive review of the status of the contemporary carbon cycle of the Arctic and its response to climate change. This review is designed to clarify key uncertainties and vulnerabilities in the response of the carbon cycle of the Arctic to ongoing climatic change. While it is clear that there are substantial stocks of carbon in the Arctic, there are also significant uncertainties associated with the magnitude of organic matter stocks contained in permafrost and the storage of methane hydrates beneath both subterranean and submerged permafrost of the Arctic. In the context of the global carbon cycle, this review demonstrates that the Arctic plays an important role in the global dynamics of both CO2 and CH4. Studies suggest that the Arctic has been a sink for atmospheric CO2 of between 0 and 0.8 Pg C/yr in recent decades, which is between 0% and 25% of the global net land/ocean flux during the 1990s. The Arctic is a substantial source of CH4 to the atmosphere (between 32 and 112 Tg CH4/yr), primarily because of the large area of wetlands throughout the region. Analyses to date indicate that the sensitivity of the carbon cycle of the Arctic during the remainder of the 21st century is highly uncertain. To improve the capability to assess the sensitivity of the carbon cycle of the Arctic to projected climate change, we recommend that (1) integrated regional studies be conducted to link observations of carbon dynamics to the processes that are likely to influence those dynamics, and (2) the understanding gained from these integrated studies be incorporated into both uncoupled and fully coupled carbon–climate modeling efforts.

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 sources and sinks.

Effects of climate extremes on the terrestrial carbon cycle: concepts, processes and potential future impacts.

PubMed

Frank, Dorothea; Reichstein, Markus; Bahn, Michael; Thonicke, Kirsten; Frank, David; Mahecha, Miguel D; Smith, Pete; van der Velde, Marijn; Vicca, Sara; Babst, Flurin; Beer, Christian; Buchmann, Nina; Canadell, Josep G; Ciais, Philippe; Cramer, Wolfgang; Ibrom, Andreas; Miglietta, Franco; Poulter, Ben; Rammig, Anja; Seneviratne, Sonia I; Walz, Ariane; Wattenbach, Martin; Zavala, Miguel A; Zscheischler, Jakob

2015-08-01

Extreme droughts, heat waves, frosts, precipitation, wind storms and other climate extremes may impact the structure, composition and functioning of terrestrial ecosystems, and thus carbon cycling and its feedbacks to the climate system. Yet, the interconnected avenues through which climate extremes drive ecological and physiological processes and alter the carbon balance are poorly understood. Here, we review the literature on carbon cycle relevant responses of ecosystems to extreme climatic events. Given that impacts of climate extremes are considered disturbances, we assume the respective general disturbance-induced mechanisms and processes to also operate in an extreme context. The paucity of well-defined studies currently renders a quantitative meta-analysis impossible, but permits us to develop a deductive framework for identifying the main mechanisms (and coupling thereof) through which climate extremes may act on the carbon cycle. We find that ecosystem responses can exceed the duration of the climate impacts via lagged effects on the carbon cycle. The expected regional impacts of future climate extremes will depend on changes in the probability and severity of their occurrence, on the compound effects and timing of different climate extremes, and on the vulnerability of each land-cover type modulated by management. Although processes and sensitivities differ among biomes, based on expert opinion, we expect forests to exhibit the largest net effect of extremes due to their large carbon pools and fluxes, potentially large indirect and lagged impacts, and long recovery time to regain previous stocks. At the global scale, we presume that droughts have the strongest and most widespread effects on terrestrial carbon cycling. Comparing impacts of climate extremes identified via remote sensing vs. ground-based observational case studies reveals that many regions in the (sub-)tropics are understudied. Hence, regional investigations are needed to allow a global upscaling of the impacts of climate extremes on global carbon-climate feedbacks. © 2015 The Authors. Global Change Biology published by John Wiley & Sons Ltd.

High-Temperature Polymer Composites Tested for Hypersonic Rocket Combustor Backup Structure

NASA Technical Reports Server (NTRS)

Sutter, James K.; Shin, E. Eugene; Thesken, John C.; Fink, Jeffrey E.

2005-01-01

Significant component weight reductions are required to achieve the aggressive thrust-toweight goals for the Rocket Based Combined Cycle (RBCC) third-generation, reusable liquid propellant rocket engine, which is one possible engine for a future single-stage-toorbit vehicle. A collaboration between the NASA Glenn Research Center and Boeing Rocketdyne was formed under the Higher Operating Temperature Propulsion Components (HOTPC) program and, currently, the Ultra-Efficient Engine Technology (UEET) Project to develop carbon-fiber-reinforced high-temperature polymer matrix composites (HTPMCs). This program focused primarily on the combustor backup structure to replace all metallic support components with a much lighter polymer-matrixcomposite- (PMC-) titanium honeycomb sandwich structure.

Quantitative assessment of the differential impacts of arbuscular and ectomycorrhiza on soil carbon cycling.

PubMed

Soudzilovskaia, Nadejda A; van der Heijden, Marcel G A; Cornelissen, Johannes H C; Makarov, Mikhail I; Onipchenko, Vladimir G; Maslov, Mikhail N; Akhmetzhanova, Asem A; van Bodegom, Peter M

2015-10-01

A significant fraction of carbon stored in the Earth's soil moves through arbuscular mycorrhiza (AM) and ectomycorrhiza (EM). The impacts of AM and EM on the soil carbon budget are poorly understood. We propose a method to quantify the mycorrhizal contribution to carbon cycling, explicitly accounting for the abundance of plant-associated and extraradical mycorrhizal mycelium. We discuss the need to acquire additional data to use our method, and present our new global database holding information on plant species-by-site intensity of root colonization by mycorrhizas. We demonstrate that the degree of mycorrhizal fungal colonization has globally consistent patterns across plant species. This suggests that the level of plant species-specific root colonization can be used as a plant trait. To exemplify our method, we assessed the differential impacts of AM : EM ratio and EM shrub encroachment on carbon stocks in sub-arctic tundra. AM and EM affect tundra carbon stocks at different magnitudes, and via partly distinct dominant pathways: via extraradical mycelium (both EM and AM) and via mycorrhizal impacts on above- and belowground biomass carbon (mostly AM). Our method provides a powerful tool for the quantitative assessment of mycorrhizal impact on local and global carbon cycling processes, paving the way towards an improved understanding of the role of mycorrhizas in the Earth's carbon cycle. © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.

Mississippi Basin Carbon Project science plan

USGS Publications Warehouse

Sundquist, E.T.; Stallard, R.F.; Bliss, N.B.; Markewich, H.W.; Harden, J.W.; Pavich, M.J.; Dean, M.D.

1998-01-01

Understanding the carbon cycle is one of the most difficult challenges facing scientists who study the global environment. Lack of understanding of global carbon cycling is perhaps best illustrated by our inability to balance the present-day global CO2 budget. The amount of CO2 produced by burning fossil fuels and by deforestation appears to exceed the amount accumulating in the atmosphere and oceans. The carbon needed to balance the CO2 budget (the so-called "missing" carbon) is probably absorbed by land plants and ultimately deposited in soils and sediments. Increasing evidence points toward the importance of these terrestrial processes in northern temperate latitudes. Thus, efforts to balance the global CO2 budget focus particular attention on terrestrial carbon uptake in our own North American "backyard."The USGS Mississippi Basin Carbon Project conducts research on the carbon budget in soils and sediments of the Mississippi River basin. The project focuses on the effects of land-use change on carbon storage and transport, nutrient cycles, and erosion and sedimentation throughout the Mississippi River Basin. Particular emphasis is placed on understanding the interactions among changes in erosion, sedimentation, and soil dynamics. The project includes spatial analysis of a wide variety of geographic data sets, estimation of whole-basin and sub-basin carbon and sediment budgets, development and implementation of terrestrial carbon-cycle models, and site-specific field studies of relevant processes. The USGS views this project as a "flagship" effort to demonstrate its capabilities to address the importance of the land surface to biogeochemical problems such as the global carbon budget.

Overview of the SMAP Applications and the SMAP Early Adopters Program - NASA's First Mission-Directed Outreach Effort

NASA Technical Reports Server (NTRS)

Escobar, V. M.; Delgado Arias, S.; Nearing, G.; Entekhabi, D.; Njoku, E.; Yueh, S.; Doorn, B.; Reichle, R.

2016-01-01

Satellite data provide global observations of many of the earths system processes and features. These data are valuable for developing scientific products that increase our understanding of how the earths systems are integrated. The water, energy and carbon cycle exchanges between the land and atmosphere are linked by soil moisture. NASAs Soil Moisture Active Passive (SMAP) mission provides soil moisture and freeze thaw measurements from space and allows scientists to link the water energy and carbon cycles. In order for SMAP data to be best integrated into decision support systems, the mission has engaged with the stakeholder community since 2009 and has attempted to scale the utility of the data to the thematic societal impacts of the satellite product applications. The SMAP Mission, which launched on January 31, 2015, has actively grown an Early Adopter (EA) community as part of its applications effort and worked with these EAs to demonstrate a scaled thematic impact of SMAP data product in societally relevant decision support applications. The SMAP mission provides global observations of the Earths surface soil moisture, providing high accuracy, resolution and continuous global coverage. Through the Early Adopters Program, the SMAP Applications Team will spend the next 2 years after launch documenting and evaluating the use of SMAP science products in applications related to weather forecasting, drought, agriculture productivity, floods, human health and national security.

Observing terrestrial ecosystems and the carbon cycle from space

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

Schimel, David; Pavlick, Ryan; Fisher, Joshua B.

2015-02-06

Modeled terrestrial ecosystem and carbon cycle feedbacks contribute substantial uncertainty to projections of future climate. The limitations of current observing networks contribute to this uncertainty. Here we present a current climatology of global model predictions and observations for photosynthesis, biomass, plant diversity and plant functional diversity. Carbon cycle tipping points occur in terrestrial regions where fluxes or stocks are largest, and where biological variability is highest, the tropics and Arctic/Boreal zones. Global observations are predominately in the mid-latitudes and are sparse in high and low latitude ecosystems. Observing and forecasting ecosystem change requires sustained observations of sufficient density in timemore » and space in critical regions. Using data and theory available now, we can develop a strategy to detect and forecast terrestrial carbon cycle-climate interactions, by combining in situ and remote techniques.« less

Electrochemical capture and release of carbon dioxide

DOE PAGES

Rheinhardt, Joseph H.; Singh, Poonam; Tarakeshwar, Pilarisetty; ...

2017-01-18

Understanding the chemistry of carbon dioxide is key to affecting changes in atmospheric concentrations. One area of intense interest is CO 2 capture in chemically reversible cycles relevant to carbon capture technologies. Most CO 2 capture methods involve thermal cycles in which a nucleophilic agent captures CO 2 from impure gas streams (e.g., flue gas), followed by a thermal process in which pure CO 2 is released. Several reviews have detailed progress in these approaches. A less explored strategy uses electrochemical cycles to capture CO 2 and release it in pure form. These cycles typically rely on electrochemical generation ofmore » nucleophiles that attack CO 2 at the electrophilic carbon atom, forming a CO 2 adduct. Then, CO 2 is released in pure form via a subsequent electrochemical step. In this Perspective, we describe electrochemical cycles for CO 2 capture and release, emphasizing electrogenerated nucleophiles. As a result, we also discuss some advantages and disadvantages inherent in this general approach.« less

Emission rates of particulate matter and elemental and organic carbon from in-use diesel engines.

PubMed

Shah, Sandip D; Cocker, David R; Miller, J Wayne; Norbeck, Joseph M

2004-05-01

Elemental carbon (EC), organic carbon (OC), and particulate matter (PM) emission rates are reported for a number of heavy heavy-duty diesel trucks (HHDDTs) and back-up generators (BUGs) operating under real-world conditions. Emission rates were determined using a unique mobile emissions laboratory (MEL) equipped with a total capture full-scale dilution tunnel connected directly to the diesel engine via a snorkel. This paper shows that PM, EC, and OC emission rates are strongly dependent on the mode of vehicle operation; highway, arterial, congested, and idling conditions were simulated by following the speed trace from the California Air Resources Board HHDDT cycle. Emission rates for BUGs are reported as a function of engine load at constant speed using the ISO 8178B Cycle D2. The EC, OC, and PM emission rates were determined to be highly variable for the HHDDTs. It was determined that the per mile emission rate of OC from a HHDDT in congested traffic is 8.1 times higher than that of an HHDDT in cruise or highway speed conditions and 1.9 times higher for EC. EC/OC ratios for BUGs (which generally operate at steady states) and HHDDTs show marked differences, indicating that the transient nature of engine operation dictates the EC/OC ratio. Overall, this research shows that the EC/OC ratio varies widely for diesel engines in trucks and BUGs and depends strongly on the operating cycle. The findings reported here have significant implications in the application of chemical mass balance modeling, diesel risk assessment, and control strategies such as the Diesel Risk Reduction Program.

Orbital pacing of carbon fluxes by a ∼9-My eccentricity cycle during the Mesozoic.

PubMed

Martinez, Mathieu; Dera, Guillaume

2015-10-13

Eccentricity, obliquity, and precession are cyclic parameters of the Earth's orbit whose climatic implications have been widely demonstrated on recent and short time intervals. Amplitude modulations of these parameters on million-year time scales induce "grand orbital cycles," but the behavior and the paleoenvironmental consequences of these cycles remain debated for the Mesozoic owing to the chaotic diffusion of the solar system in the past. Here, we test for these cycles from the Jurassic to the Early Cretaceous by analyzing new stable isotope datasets reflecting fluctuations in the carbon cycle and seawater temperatures. Our results document a prominent cyclicity of ∼9 My in the carbon cycle paced by changes in the seasonal dynamics of hydrological processes and long-term sea level fluctuations. These paleoenvironmental changes are linked to a great eccentricity cycle consistent with astronomical solutions. The orbital forcing signal was mainly amplified by cumulative sequestration of organic matter in the boreal wetlands under greenhouse conditions. Finally, we show that the ∼9-My cycle faded during the Pliensbachian, which could either reflect major paleoenvironmental disturbances or a chaotic transition affecting this cycle.

Drivers of the Seasonal Carbon Cycle in the Coastal Gulf of Alaska

NASA Astrophysics Data System (ADS)

Pilcher, D.; Siedlecki, S. A.; Hermann, A. J.; Coyle, K. O.; Mathis, J. T.

2016-02-01

The Coastal Gulf of Alaska serves as a significant carbon sink annually, but varies seasonally from net carbon efflux in winter, to net carbon uptake from spring through fall. This significant uptake of anthropogenic CO2 combined with the naturally cold, low calcium carbonate surface waters is expected to accelerate ocean acidification. Observational evidence has already detected subsurface aragonite undersaturation, likely resulting from carbon remineralization of sinking organic matter. Other processes such as storm-induced vertical mixing, glacial runoff, temperature change, and nutrient supply can further modify the carbon cycle. Improving knowledge of these seasonal processes is critical for the region's fisheries that provide substantial ecosystem services and can be adversely impacted by sub-optimal aragonite saturation conditions. We use a regional model of the Coastal Gulf of Alaska coupled to an ecosystem model with full carbonate chemistry to investigate the physical and biogeochemical mechanisms that drive the seasonal carbon cycle. Boundary conditions are set from the coarser Northeast Pacific model, with alkalinity and carbon concentrations determined from empirical relationships with salinity. Model output from a 2009 hindcast simulation is compared to observations of alkalinity and dissolved inorganic carbon concentrations for model verification and to elucidate seasonal mechanisms.

The effects of sea level and palaeotopography on lithofacies distribution and geometries in heterozoan carbonates, south-eastern Spain

USGS Publications Warehouse

Johnson, C.L.; Franseen, E.K.; Goldstein, R.H.

2005-01-01

This study utilized three-dimensional exposures to evaluate how sea-level position and palaeotopography control the facies and geometries of heterozoan carbonates. Heterozoan carbonates were deposited on top of a Neogene volcanic substrate characterized by palaeotopographic highs, palaeovalleys, and straits that were formed by subaerial erosion, possibly original volcanic topography, and faults prior to carbonate deposition. The depositional sequence that is the focus of this study (DS1B) consists of 7-10 fining upward cycles that developed in response to relative sea-level fluctuations. A complete cycle has a basal erosion surface overlain by deposits of debrisflows and high-density turbidity currents, which formed during relative sea-level fall. Overlying tractive deposits most likely formed during the lowest relative position of sea level. Overlying these are debrites grading upward to high-density turbidites and low-density turbidites that formed during relative sea-level rise. The tops of the cycles consist of hemipelagic deposits that formed during the highest relative position of sea level. The cycles fine upward because upslope carbonate production decreased as relative sea level rose due to less surface area available for shallow-water carbonate production and partial drowning of substrates. The cycles are dominated by two end-member types of facies associations and stratal geometries that formed in response to fluctuating sea-level position over variable substrate palaeotopography. One end-member is termed 'flank flow cycle' because this type of cycle indicates dominant sediment transport down the flanks of palaeovalleys. Those cycles drape the substrate, have more debrites, high-density turbidites and erosion on palaeovalley flanks, and in general, the lithofacies fine down the palaeovalley flanks into the palaeovalley axes. The second end-member is termed 'axial flow cycle' because it indicates a dominance of sediment transport down the axes of palaeovalleys. Those cycles are characterized by debrites and high-density turbidites in palaeovalley axes, and lap out of strata against the flanks of palaeovalleys. Where and when an axial flow cycle or flank flow cycle developed appears to be related to the intersection of sea level with areas of gentle or steep substrate slopes, during an overall relative rise in sea level. Results from this study provide a model for similar systems that must combine carbonate principles for sediment production, palaeotopographic controls, and physical principles of sediment remobilization into deep water. ?? 2005 International Association of Sedimentologists.

Ocean Carbon and Biogeochemistry Scoping Workshop on Terrestrial and Coastal Carbon Fluxes in the Gulf of Mexico, St. Petersburg, FL

NASA Technical Reports Server (NTRS)

Robbins, L. L.; Coble, P. G.; Clayton, T. D.; Cai, W. J.

2008-01-01

Despite their relatively small surface area, ocean margins may have a significant impact on global biogeochemical cycles and, potentially, the global air-sea fluxes of carbon dioxide. Margins are characterized by intense geochemical and biological processing of carbon and other elements and exchange large amounts of matter and energy with the open ocean. The area-specific rates of productivity, biogeochemical cycling, and organic/inorganic matter sequestration are high in coastal margins, with as much as half of the global integrated new production occurring over the continental shelves and slopes (Walsh, 1991; Doney and Hood, 2002; Jahnke, in press). However, the current lack of knowledge and understanding of biogeochemical processes occurring at the ocean margins has left them largely ignored in most of the previous global assessments of the oceanic carbon cycle (Doney and Hood, 2002). A major source of North American and global uncertainty is the Gulf of Mexico, a large semi-enclosed subtropical basin bordered by the United States, Mexico, and Cuba. Like many of the marginal oceans worldwide, the Gulf of Mexico remains largely unsampled and poorly characterized in terms of its air-sea exchange of carbon dioxide and other carbon fluxes. The goal of the workshop was to bring together researchers from multiple disciplines studying terrestrial, aquatic, and marine ecosystems to discuss the state of knowledge in carbon fluxes in the Gulf of Mexico, data gaps, and overarching questions in the Gulf of Mexico system. The discussions at the workshop were intended to stimulate integrated studies of marine and terrestrial biogeochemical cycles and associated ecosystems that will help to establish the role of the Gulf of Mexico in the carbon cycle and how it might evolve in the face of environmental change.

Modelling the Phanerozoic carbon cycle and climate: constraints from the 87Sr/86Sr isotopic ratio of seawater

NASA Technical Reports Server (NTRS)

Francois, L. M.; Walker, J. C.

1992-01-01

A numerical model describing the coupled evolution of the biogeochemical cycles of carbon, sulfur, calcium, magnesium, phosphorus, and strontium has been developed to describe the long-term changes of atmospheric carbon dioxide and climate during the Phanerozoic. The emphasis is on the effects of coupling the cycles of carbon and strontium. Various interpretations of the observed Phanerozoic history of the seawater 87Sr/86Sr ratio are investigated with the model. More specifically, the abilities of continental weathering, volcanism, and surface lithology in generating that signal are tested and compared. It is suggested that the observed fluctuations are mostly due to a changing weatherability over time. It is shown that such a conclusion is very important for the modelling of the carbon cycle. Indeed, it implies that the conventional belief that the evolution of atmospheric carbon dioxide and climate on a long time scale is governed by the balance between the volcanic input of CO2 and the rate of silicate weathering is not true. Rather carbon exchanges between the mantle and the exogenic system are likely to have played a key role too. Further, the increase of the global weathering rates with increasing surface temperature and/or atmospheric CO2 pressure usually postulated in long-term carbon cycle and climate modelling is also inconsistent with the new model. Other factors appear to have modulated the weatherability of the continents through time, such as mountain building and the existence of glaciers and ice sheets. Based on these observations, a history of atmospheric carbon dioxide and climate during Phanerozoic time, consistent with the strontium isotopic data, is reconstructed with the model and is shown to be compatible with paleoclimatic indicators, such as the timing of glaciation and the estimates of Cretaceous paleotemperatures.

GEO Carbon and GHG Initiative Task 3: Optimizing in-situ measurements of essential carbon cycle variables across observational networks

NASA Astrophysics Data System (ADS)

Durden, D.; Muraoka, H.; Scholes, R. J.; Kim, D. G.; Loescher, H. W.; Bombelli, A.

2017-12-01

The development of an integrated global carbon cycle observation system to monitor changes in the carbon cycle, and ultimately the climate system, across the globe is of crucial importance in the 21stcentury. This system should be comprised of space and ground-based observations, in concert with modelling and analysis, to produce more robust budgets of carbon and other greenhouse gases (GHGs). A global initiative, the GEO Carbon and GHG Initiative, is working within the framework of Group on Earth Observations (GEO) to promote interoperability and provide integration across different parts of the system, particularly at domain interfaces. Thus, optimizing the efforts of existing networks and initiatives to reduce uncertainties in budgets of carbon and other GHGs. This is a very ambitious undertaking; therefore, the initiative is separated into tasks to provide actionable objectives. Task 3 focuses on the optimization of in-situ observational networks. The main objective of Task 3 is to develop and implement a procedure for enhancing and refining the observation system for identified essential carbon cycle variables (ECVs) that meets user-defined specifications at minimum total cost. This work focuses on the outline of the implementation plan, which includes a review of essential carbon cycle variables and observation technologies, mapping the ECVs performance, and analyzing gaps and opportunities in order to design an improved observing system. A description of the gap analysis of in-situ observations that will begin in the terrestrial domain to address issues of missing coordination and large spatial gaps, then extend to ocean and atmospheric observations in the future, will be outlined as the subsequent step to landscape mapping of existing observational networks.

Global Night-Time Lights for Observing Human Activity

NASA Technical Reports Server (NTRS)

Hipskind, Stephen R.; Elvidge, Chris; Gurney, K.; Imhoff, Mark; Bounoua, Lahouari; Sheffner, Edwin; Nemani, Ramakrishna R.; Pettit, Donald R.; Fischer, Marc

2011-01-01

We present a concept for a small satellite mission to make systematic, global observations of night-time lights with spatial resolution suitable for discerning the extent, type and density of human settlements. The observations will also allow better understanding of fine scale fossil fuel CO2 emission distribution. The NASA Earth Science Decadal Survey recommends more focus on direct observations of human influence on the Earth system. The most dramatic and compelling observations of human presence on the Earth are the night light observations taken by the Defence Meteorological System Program (DMSP) Operational Linescan System (OLS). Beyond delineating the footprint of human presence, night light data, when assembled and evaluated with complementary data sets, can determine the fine scale spatial distribution of global fossil fuel CO2 emissions. Understanding fossil fuel carbon emissions is critical to understanding the entire carbon cycle, and especially the carbon exchange between terrestrial and oceanic systems.

Modeling Oceanic Primary Production: Photoacclimation and Nutrient Effects on Light-saturated Photosynthesis

NASA Technical Reports Server (NTRS)

Behrenfeld, Michael J.; Maranon, Emilio; Siegel, David A.; Hooker, Stanford B.

2000-01-01

In this report, we describe a new model (the 'PhotoAcc' model) for estimating changes in the light-saturated rate of chlorophyll-normalized phytoplankton carbon fixation (Pbmax). The model is based on measurements conducted during the Atlantic Meridional Transect studies and the Bermuda Time Series program. The PhotoAcc model explained 64% to 82% of the observed variability in Pbmax for our data set, whereas none of the previously published Pbmax models described over the past 44 years explained any of the variance. The significance of this result is that a primary limiting factor for extracting ocean carbon fixation rates from satellite measurements of near surface chlorophyll has been errors in the estimate of Pbmax. Our new model should thus result in much improved calculations of oceanic photosynthesis and thus the role of the oceans in the global carbon cycle.

ARM Airborne Carbon Measurements VI (ARM-ACME VI) Field Campaign Report

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

Biraud, Sebastien

2017-05-01

From October 1, 2015 through September 30, 2016, AAF deployed a Cessna 206 aircraft over the Southern Great Plains, collecting observations of trace gas mixing ratios over the ARM/SGP Central Facility. The aircraft payload included two Atmospheric Observing Systems (AOS Inc.) analyzers for continuous measurements of CO2, and a 12-flask sampler for analysis of carbon cycle gases (CO2, CO, CH4, N2O, 13CO2). The aircraft payload also includes solar/infrared radiation measurements. This research (supported by DOE ARM and TES programs) builds upon previous ARM-ACME missions. The goal of these measurements is to improve understanding of: (a) the carbon exchange of themore » ARM region; (b) how CO2 and associated water and energy fluxes influence radiative forcing, convective processes, and CO2 concentrations over the ARM region, and (c) how greenhouse gases are transported on continental scales.« less

Insights from Modeling the Integrated Climate, Biogeochemical Cycles, Human Activities and Their Interactions in the ACME Earth System Model

NASA Astrophysics Data System (ADS)

Leung, L. R.; Thornton, P. E.; Riley, W. J.; Calvin, K. V.

2017-12-01

Towards the goal of understanding the contributions from natural and managed systems to current and future greenhouse gas fluxes and carbon-climate and carbon-CO2 feedbacks, efforts have been underway to improve representations of the terrestrial, river, and human components of the ACME earth system model. Broadly, our efforts include implementation and comparison of approaches to represent the nutrient cycles and nutrient limitations on ecosystem production, extending the river transport model to represent sediment and riverine biogeochemistry, and coupling of human systems such as irrigation, reservoir operations, and energy and land use with the ACME land and river components. Numerical experiments have been designed to understand how terrestrial carbon, nitrogen, and phosphorus cycles regulate climate system feedbacks and the sensitivity of the feedbacks to different model treatments, examine key processes governing sediment and biogeochemistry in the rivers and their role in the carbon cycle, and exploring the impacts of human systems in perturbing the hydrological and carbon cycles and their interactions. This presentation will briefly introduce the ACME modeling approaches and discuss preliminary results and insights from numerical experiments that lay the foundation for improving understanding of the integrated climate-biogeochemistry-human system.

Enhanced seasonal CO2 exchange caused by amplified plant productivity in northern ecosystems.

PubMed

Forkel, Matthias; Carvalhais, Nuno; Rödenbeck, Christian; Keeling, Ralph; Heimann, Martin; Thonicke, Kirsten; Zaehle, Sönke; Reichstein, Markus

2016-02-12

Atmospheric monitoring of high northern latitudes (above 40°N) has shown an enhanced seasonal cycle of carbon dioxide (CO2) since the 1960s, but the underlying mechanisms are not yet fully understood. The much stronger increase in high latitudes relative to low ones suggests that northern ecosystems are experiencing large changes in vegetation and carbon cycle dynamics. We found that the latitudinal gradient of the increasing CO2 amplitude is mainly driven by positive trends in photosynthetic carbon uptake caused by recent climate change and mediated by changing vegetation cover in northern ecosystems. Our results underscore the importance of climate-vegetation-carbon cycle feedbacks at high latitudes; moreover, they indicate that in recent decades, photosynthetic carbon uptake has reacted much more strongly to warming than have carbon release processes. Copyright © 2016, American Association for the Advancement of Science.

Wind farm and solar park effects on plant–soil carbon cycling: uncertain impacts of changes in ground-level microclimate

PubMed Central

Armstrong, Alona; Waldron, Susan; Whitaker, Jeanette; Ostle, Nicholas J

2014-01-01

Global energy demand is increasing as greenhouse gas driven climate change progresses, making renewable energy sources critical to future sustainable power provision. Land-based wind and solar electricity generation technologies are rapidly expanding, yet our understanding of their operational effects on biological carbon cycling in hosting ecosystems is limited. Wind turbines and photovoltaic panels can significantly change local ground-level climate by a magnitude that could affect the fundamental plant–soil processes that govern carbon dynamics. We believe that understanding the possible effects of changes in ground-level microclimates on these phenomena is crucial to reducing uncertainty of the true renewable energy carbon cost and to maximize beneficial effects. In this Opinions article, we examine the potential for the microclimatic effects of these land-based renewable energy sources to alter plant–soil carbon cycling, hypothesize likely effects and identify critical knowledge gaps for future carbon research. PMID:24132939

40 CFR 600.114-08 - Vehicle-specific 5-cycle fuel economy and carbon-related exhaust emission calculations.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 30 2011-07-01 2011-07-01 false Vehicle-specific 5-cycle fuel economy... Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) ENERGY POLICY FUEL ECONOMY AND CARBON-RELATED EXHAUST EMISSIONS OF MOTOR VEHICLES Fuel Economy and Carbon-Related Exhaust Emission Regulations for 1978 and Later...

Development of a prototype regenerable carbon dioxide absorber

NASA Technical Reports Server (NTRS)

Onischak, M.

1976-01-01

Design information was obtained for a new, regenerable carbon dioxide control system for extravehicular activity life support systems. Solid potassium carbonate was supported in a thin porous sheet form and fabricated into carbon dioxide absorber units. Carbon dioxide and water in the life support system atmosphere react with the potassium carbonate and form potassium bicarbonate. The bicarbonate easily reverts to the carbonate by heating to 150 deg C. The methods of effectively packing the sorbent material into EVA-sized units and the effects of inlet concentrations, flowrate, and temperature upon performance were investigated. The cycle life of the sorbent upon the repeated thermal regenerations was demonstrated through 90 cycles.

Drivers of multi-century trends in the atmospheric CO2 mean annual cycle in a prognostic ESM

NASA Astrophysics Data System (ADS)

Liptak, Jessica; Keppel-Aleks, Gretchen; Lindsay, Keith

2017-03-01

The amplitude of the mean annual cycle of atmospheric CO2 is a diagnostic of seasonal surface-atmosphere carbon exchange. Atmospheric observations show that this quantity has increased over most of the Northern Hemisphere (NH) extratropics during the last 3 decades, likely from a combination of enhanced atmospheric CO2, climate change, and anthropogenic land use change. Accurate climate prediction requires accounting for long-term interactions between the environment and carbon cycling; thus, analysis of the evolution of the mean annual cycle in a fully prognostic Earth system model may provide insight into the multi-decadal influence of environmental change on the carbon cycle. We analyzed the evolution of the mean annual cycle in atmospheric CO2 simulated by the Community Earth System Model (CESM) from 1950 to 2300 under three scenarios designed to separate the effects of climate change, atmospheric CO2 fertilization, and land use change. The NH CO2 seasonal amplitude increase in the CESM mainly reflected enhanced primary productivity during the growing season due to climate change and the combined effects of CO2 fertilization and nitrogen deposition over the mid- and high latitudes. However, the simulations revealed shifts in key climate drivers of the atmospheric CO2 seasonality that were not apparent before 2100. CO2 fertilization and nitrogen deposition in boreal and temperate ecosystems were the largest contributors to mean annual cycle amplification over the midlatitudes for the duration of the simulation (1950-2300). Climate change from boreal ecosystems was the main driver of Arctic CO2 annual cycle amplification between 1950 and 2100, but CO2 fertilization had a stronger effect on the Arctic CO2 annual cycle amplitude during 2100-2300. Prior to 2100, the NH CO2 annual cycle amplitude increased in conjunction with an increase in the NH land carbon sink. However, these trends decoupled after 2100, underscoring that an increasing atmospheric CO2 annual cycle amplitude does not necessarily imply a strengthened terrestrial carbon sink.

Astronomical tunings of the Oligocene-Miocene transition from Pacific Ocean Site U1334 and implications for the carbon cycle

NASA Astrophysics Data System (ADS)

Beddow, Helen M.; Liebrand, Diederik; Wilson, Douglas S.; Hilgen, Frits J.; Sluijs, Appy; Wade, Bridget S.; Lourens, Lucas J.

2018-03-01

Astronomical tuning of sediment sequences requires both unambiguous cycle pattern recognition in climate proxy records and astronomical solutions, as well as independent information about the phase relationship between these two. Here we present two different astronomically tuned age models for the Oligocene-Miocene transition (OMT) from Integrated Ocean Drilling Program Site U1334 (equatorial Pacific Ocean) to assess the effect tuning has on astronomically calibrated ages and the geologic timescale. These alternative age models (roughly from ˜ 22 to ˜ 24 Ma) are based on different tunings between proxy records and eccentricity: the first age model is based on an aligning CaCO3 weight (wt%) to Earth's orbital eccentricity, and the second age model is based on a direct age calibration of benthic foraminiferal stable carbon isotope ratios (δ13C) to eccentricity. To independently test which tuned age model and associated tuning assumptions are in best agreement with independent ages based on tectonic plate-pair spreading rates, we assign the tuned ages to magnetostratigraphic reversals identified in deep-marine magnetic anomaly profiles. Subsequently, we compute tectonic plate-pair spreading rates based on the tuned ages. The resultant alternative spreading-rate histories indicate that the CaCO3 tuned age model is most consistent with a conservative assumption of constant, or linearly changing, spreading rates. The CaCO3 tuned age model thus provides robust ages and durations for polarity chrons C6Bn.1n-C7n.1r, which are not based on astronomical tuning in the latest iteration of the geologic timescale. Furthermore, it provides independent evidence that the relatively large (several 10 000 years) time lags documented in the benthic foraminiferal isotope records relative to orbital eccentricity constitute a real feature of the Oligocene-Miocene climate system and carbon cycle. The age constraints from Site U1334 thus indicate that the delayed responses of the Oligocene-Miocene climate-cryosphere system and (marine) carbon cycle resulted from highly non-linear feedbacks to astronomical forcing.

How does soil erosion influence the terrestrial carbon cycle and the impacts of land use and land cover change?

NASA Astrophysics Data System (ADS)

Naipal, V.; Wang, Y.; Ciais, P.; Guenet, B.; Lauerwald, R.

2017-12-01

The onset of agriculture has accelerated soil erosion rates significantly, mobilizing vast quantities of soil organic carbon (SOC) globally. Studies show that at timescales of decennia to millennia this mobilized SOC can significantly alter previously estimated carbon emissions from land use and land cover change (LULCC). However, a full understanding of the impact of soil erosion on land-atmosphere carbon exchange is still missing. The aim of our study is to better constrain the terrestrial carbon fluxes by developing methods, which are compatible with earth system models (ESMs), and explicitly represent the links between soil erosion and carbon dynamics. For this we use an emulator that represents the carbon cycle of ORCHIDEE, which is the land component of the IPSL ESM, in combination with an adjusted version of the Revised Universal Soil Loss Equation (RUSLE) model. We applied this modeling framework at the global scale to evaluate how soil erosion influenced the terrestrial carbon cycle in the presence of elevated CO2, regional climate change and land use change. Here, we focus on the effects of soil detachment by erosion only and do not consider sediment transport and deposition. We found that including soil erosion in the SOC dynamics-scheme resulted in two times more SOC being lost during the historical period (1850-2005 AD). LULCC is the main contributor to this SOC loss, whose impact on the SOC stocks is significantly amplified by erosion. Regionally, the influence of soil erosion varies significantly, depending on the magnitude of the perturbations to the carbon cycle and the effects of LULCC and climate change on soil erosion rates. We conclude that it is necessary to include soil erosion in assessments of LULCC, and to explicitly consider the effects of elevated CO2 and climate change on the carbon cycle and on soil erosion, for better quantification of past, present, and future LULCC carbon emissions.

Soil erosion, sedimentation and the carbon cycle

NASA Astrophysics Data System (ADS)

Cammeraat, L. H.; Kirkels, F.; Kuhn, N. J.

2012-04-01

Historically soil erosion focused on the effects of on-site soil quality loss and consequently reduced crop yields, and off-site effects related to deposition of material and water quality issues such as increased sediment loads of rivers. In agricultural landscapes geomorphological processes reallocate considerable amounts of soil and soil organic carbon (SOC). The destiny of SOC is of importance because it constitutes the largest C pool of the fast carbon cycle, and which cannot only be understood by looking at the vertical transfer of C from soil to atmosphere. Therefore studies have been carried out to quantify this possible influence of soil erosion and soil deposition and which was summarized by Quinton et al. (2010) by "We need to consider soils as mobile systems to make accurate predictions about the consequences of global change for terrestrial biogeochemical cycles and climate feedbacks". Currently a debate exists on the actual fate of SOC in relation to the global carbon cycle, represented in a controversy between researchers claiming that erosion is a sink, and those who claim the opposite. This controversy is still continuing as it is not easy to quantify and model the dominating sink and source processes at the landscape scale. Getting insight into the balance of the carbon budget requires a comprehensive research of all relevant processes at broad spatio-temporal scales, from catchment to regional scales and covering the present to the late Holocene. Emphasising the economic and societal benefits, the merits for scientific knowledge of the carbon cycle and the potential to sequester carbon and consequently offset increasing atmospheric CO2 concentrations, make the fate of SOC in agricultural landscapes a high-priority research area. Quinton, J.N., Govers, G., Van Oost, K., Bardgett, R.D., 2010. The impact of agricultural soil erosion on biogeochemical cycling. Nature Geosci, 3, 311-314.

The late Precambrian greening of the Earth.

PubMed

Knauth, L Paul; Kennedy, Martin J

2009-08-06

Many aspects of the carbon cycle can be assessed from temporal changes in the (13)C/(12)C ratio of oceanic bicarbonate. (13)C/(12)C can temporarily rise when large amounts of (13)C-depleted photosynthetic organic matter are buried at enhanced rates, and can decrease if phytomass is rapidly oxidized or if low (13)C is rapidly released from methane clathrates. Assuming that variations of the marine (13)C/(12)C ratio are directly recorded in carbonate rocks, thousands of carbon isotope analyses of late Precambrian examples have been published to correlate these otherwise undatable strata and to document perturbations to the carbon cycle just before the great expansion of metazoan life. Low (13)C/(12)C in some Neoproterozoic carbonates is considered evidence of carbon cycle perturbations unique to the Precambrian. These include complete oxidation of all organic matter in the ocean and complete productivity collapse such that low-(13)C/(12)C hydrothermal CO(2) becomes the main input of carbon. Here we compile all published oxygen and carbon isotope data for Neoproterozoic marine carbonates, and consider them in terms of processes known to alter the isotopic composition during transformation of the initial precipitate into limestone/dolostone. We show that the combined oxygen and carbon isotope systematics are identical to those of well-understood Phanerozoic examples that lithified in coastal pore fluids, receiving a large groundwater influx of photosynthetic carbon from terrestrial phytomass. Rather than being perturbations to the carbon cycle, widely reported decreases in (13)C/(12)C in Neoproterozoic carbonates are more easily interpreted in the same way as is done for Phanerozoic examples. This influx of terrestrial carbon is not apparent in carbonates older than approximately 850 Myr, so we infer an explosion of photosynthesizing communities on late Precambrian land surfaces. As a result, biotically enhanced weathering generated carbon-bearing soils on a large scale and their detrital sedimentation sequestered carbon. This facilitated a rise in O(2) necessary for the expansion of multicellular life.

TThe role of nitrogen availability in land-atmosphere interactions: a systematic evaluation of carbon-nitrogen coupling in a global land surface model using plot-level nitrogen fertilization experiments

NASA Astrophysics Data System (ADS)

Thomas, R. Q.; Goodale, C. L.; Bonan, G. B.; Mahowald, N. M.; Ricciuto, D. M.; Thornton, P. E.

2010-12-01

Recent research from global land surface models emphasizes the important role of nitrogen cycling on global climate, via its control on the terrestrial carbon balance. Despite the implications of nitrogen cycling on global climate predictions, the research community has not performed a systematic evaluation of nitrogen cycling in global models. Here, we present such an evaluation for one global land model, CLM-CN. In the evaluation we simulated 45 plot-scale nitrogen-fertilization experiments distributed across 33 temperate and boreal forest sites. Model predictions were evaluated against field observations by comparing the vegetation and soil carbon responses to the additional nitrogen. Aggregated across all experiments, the model predicted a larger vegetation carbon response and a smaller soil carbon response than observed; the responses partially offset each other, leading to a slightly larger total ecosystem carbon response than observed. However, the model-observation agreement improved for vegetation carbon when the sites with observed negative carbon responses to nitrogen were excluded, which may be because the model lacks mechanisms whereby nitrogen additions increase tree mortality. Among experiments, younger forests and boreal forests’ vegetation carbon responses were less than predicted and mature forests (> 40 years old) were greater than predicted. Specific to the CLM-CN, this study used a systematic evaluation to identify key areas to focus model development, especially soil carbon- nitrogen interactions and boreal forest nitrogen cycling. Applicable to the modeling community, this study demonstrates a standardized protocol for comparing carbon-nitrogen interactions among global land models.

Carbon-Carbon Recuperators in Closed-Brayton-Cycle Space Power Systems

NASA Technical Reports Server (NTRS)

Barrett, Michael J.; Johnson, Paul K.

2006-01-01

The use of carbon-carbon (C-C) recuperators in closed-Brayton-cycle space power conversion systems was assessed. Recuperator performance was forecast based on notional thermodynamic cycle state values for planetary missions. Resulting thermal performance, mass and volume for plate-fin C-C recuperators were estimated and quantitatively compared with values for conventional offset-strip-fin metallic designs. Mass savings of 40-55% were projected for C-C recuperators with effectiveness greater than 0.9 and thermal loads from 25-1400 kWt. The smaller thermal loads corresponded with lower mass savings; however, at least 50% savings were forecast for all loads above 300 kWt. System-related material challenges and compatibility issues were also discussed.

The Use of Remote Sensing Data for Advancing America's Energy Policy

NASA Technical Reports Server (NTRS)

Valinia, Azita; Seery, Bernard D.

2010-01-01

After briefly reviewing America's Energy Policy laid out by the Obama Administration, we outline how a Global Carbon Observing System designed to monitor Carbon from space can provide the necessary data and tools to equip decision makers with the knowledge necessary to formulate effective energy use and practices policy. To stabilize greenhouse gas emissions in the atmosphere in a manner that it does not interfere with the Earth's climate system (which is one of the goals of United Nations Framework for Convention on Climate Change) requires vastly improved prediction of the atmospheric carbon dioxide (CO2) concentrations. This in torn requires a robust understanding of the carbon exchange mechanisms between atmosphere, land, and oceans and a clear understanding of the sources and sinks (i.e. uptake and storage) of CO2. We discuss how the Carbon Observing System from space aids in better understanding of the connection between the carbon cycle and climate change and provides more accurate predictions of atmospheric CO2 concentration. It also enables implementation of greenhouse gas (GHG) mitigation policies such as cap and trade programs, international climate treaties, as well as formulation of effective energy use policies.

Carbon footprint estimation of municipal water cycle

NASA Astrophysics Data System (ADS)

Bakhshi, Ali A.

2009-11-01

This research investigates the embodied energy associated with water use. A geographic information system (GIS) was tested using data from Loudoun County, Virginia. The objective of this study is to estimate the embodied energy and carbon emission levels associated with water service at a geographical location and to improve for sustainability planning. Factors that affect the carbon footprint were investigated and the use of a GIS based model as a sustainability planning framework was evaluated. The carbon footprint metric is a useful tool for prediction and measurement of a system's sustainable performance over its expected life cycle. Two metrics were calculated: tons of carbon dioxide per year to represent the contribution to global warming and watt-hrs per gallon to show the embodied energy associated with water consumption. The water delivery to the building, removal of wastewater from the building and associated treatment of water and wastewater create a sizable carbon footprint; often the energy attributed to this water service is the greatest end use of electrical energy. The embodied energy in water depends on topographical characteristics of the area's local water supply, the efficiency of the treatment systems, and the efficiency of the pumping stations. The questions answered by this research are: What is the impact of demand side sustainable water practices on the embodied energy as represented by a comprehensive carbon footprint? What are the major energy consuming elements attributed to the system? What is a viable and visually identifiable tool to estimate the carbon footprint attributed to those Greenhouse Gas (GHG) producing elements? What is the embodied energy and emission associated with water use delivered to a building? Benefits to be derived from a standardized GIS applied carbon footprint estimation approach include: (1) Improved environmental and economic information for the developers, water and wastewater processing and municipal planners; (2) Improved energy use reporting and conservation planning; (3) Establishment of a benchmark for GHG emissions attributed to the water and wastewater industry; (4) Ability to quantify relative impacts of building design options using carbon emission equivalents. The GIS based model was applied to the Dulles South and Brambelton regions in Loudoun County, Virginia. The GIS revealed the customer's embodied energy to be in the range of 4.41MWh/Mgal to 8.0 MWh/Mgal. The customer's carbon footprint is between 0.008 and18.0 Tons of CO2 for year 2008. The results of this study contributed to development of a standardized approach to estimate the GHG impact of a total water cycle, and provided a viable GIS tool resulting in visual maps as a decision support. It also showed the use of derived empirical formulas in predication of GHG impact for end users in a specific geographical area. The embodied energy in delivered water can be estimated using the devised model and be considered by the building sustainability ranking programs such as the USGBC LEED rating system. KEYWORDS. Water Life Cycle, Embodied Energy, Global Warming Potential, Energy Intensity, Energy Intensity Matrix, Emission Intensity, Emission Coefficient, Carbon Dioxide Emission, Water and Wastewater, Collection, Treatment and Distribution, Carbon Footprint, Topography, Municipality, Environmental Indicator, ArcGIS, LEED, GHG, ESI, LCA, LCEA, LCI, Sustainability, End Use, Potable Water

The role of pCO2 in astronomically-paced climate and carbon cycle variations in the Middle Miocene

NASA Astrophysics Data System (ADS)

Penman, D. E.; Hull, P. M.; Scher, H.; Kirtland Turner, S.; Ridgwell, A.

2017-12-01

The pace of Earth's background climate variability is known to be driven by the Milankovitch cycles, variations in Earth's orbital parameters and axial tilt. While the Milankovitch (orbital) theory of climate change is very nearly universally accepted, the climate system mechanisms and feedbacks responsible for amplifying orbital cycles preserved in the geologic record remain uncertain. For the late Pleistocene, the ice core-derived record of atmospheric carbon dioxide (pCO2) is strongly coupled with global temperature on orbital time scales, indicating that internal feedbacks involving the carbon cycle amplify or even cause the large changes in global temperature during orbitally driven glacial-interglacial cycles. However, for earlier time periods beyond the range of ice cores (the last 800 kyr), it is not possible to directly compare records of pCO2 to orbital climate cycles because there are no high-resolution (orbitally resolved) records of pCO2 before the Pliocene. We address this deficiency with a high-resolution ( 5-10 kyr spacing) record of planktonic foraminiferal d11B-derived surface seawater pH (as well as d13C and trace metal analyses) over a 500 kyr time window in a sedimentary record with known Milankovitch-scale climate and carbon cycle oscillations: the Middle Miocene (14.0 - 14.5 Ma) at ODP Site 926 (subtropical North Atlantic). The resulting pH record can be used to constrain atmospheric pCO2, allowing comparison of the timescale and magnitude of carbon cycle changes during a period of eccentricity-dominated variability in the response of the global climate system (the Late Pleistocene) with a period of obliquity-dominance (the middle Miocene). These new records of planktic d11B and d13C will then be used to guide simulations of astronomical climate forcing in Earth System models, resulting in refined estimates of pCO2 changes over orbital cycles and providing quantitative constraints on the mechanisms and feedbacks responsible for the Milankovitch control of climate and carbon cycling.

The Change of Climate and Terrestrial Carbon Cycle over Tibetan Plateau in CMIP5 Models

NASA Astrophysics Data System (ADS)

Li, S.

2015-12-01

Six earth system models from phase 5 of the Coupled Model Intercomparison Project (CMIP5) are evaluated over Tibetan Plateau (TP) by comparing the modeled temperature (Tas), precipitation (Pr), net primary production (NPP) and leaf area index (LAI) with the observed Tas, Pr, IGBP NPP and MPIM LAI in the historical, and then we analyzed the change of climate and carbon cycle and explored the relationship between the carbon cycle and main climatic drivers in the historical and representative concentration pathway 4.5 (RCP4.5) simulation over TP. While model results differ, their region spatial distributions from 1971 to 2000 agree reasonably with observed Tas, Pr and proxy LAI and NPP. The climatic variables, LAI and carbon flux vary between two simulations, the ration of NPP to gross primary production (GPP) does not change much in the historical and RCP4.5 scenarios. The linear trends of LAI and carbon flux show an obvious continuous increase from historical climatic period (1971-2000) to the first two climatic periods (2011-2040; 2041-2700) of RCP4.5, then the trends decrease in the third climatic period (2071-2100) of RCP4.5. The cumulative multi model ensemble (MME) net biome production (NBP) is 0.32 kgCm-2yr-1 during 1850 to 2005 and 1.43 kgCm-2yr-1 during 2006 to 2100, the Tibetan Plateau is a carbon sink during the historical scenario, and TP will uptake more carbon from atmosphere during 2006 to 2100 than 1850 to 2005 under RCP4.5 scenario. LAI, GPP, NPP, Ra and Rh appear more related to the Tas than Pr and Rsds, and the Tas is the primary climatic driver for the plant growth and carbon cycle. With the climate change in twenty-first century under RCP4.5 scenario, Tas still is the primary climate driver for the plant growth and carbon cycle, but the effect of temperature on plant growth and carbon cycle gets weaker.

Emission patterns of diesel-powered passenger cars. Part II

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

Braddock, J.N.; Gabele, P.A.

An experimental program was conducted to characterize the gaseous and particulate emissions from a 1975 Peugeot 504D light duty diesel-powered vehicle. The vehicle was tested over the 1975 Federal Test Procedure, Highway Fuel Economy Test, and Sulfate Emissions Test driving cycles using four different fuels covering a fair range of composition, density, and sulfur content. In addition to fuel economy and regulated gaseous emission measurements of hydrocarbons, carbon monoxide, and oxides of nitrogen, emission measurements were also obtained for non-regulated pollutants including sulfur dioxide, sulfates, aldehydes, benzo(a)pyrene, carbonyl sulfide, hydrogen cyanide, nonreactive hydrocarbons, and particulate matter. The results are discussedmore » in terms of emission trends due to either fuel type or driving cycle influence.« less

Solution-grown silicon nanowires for lithium-ion battery anodes.

PubMed

Chan, Candace K; Patel, Reken N; O'Connell, Michael J; Korgel, Brian A; Cui, Yi

2010-03-23

Composite electrodes composed of silicon nanowires synthesized using the supercritical fluid-liquid-solid (SFLS) method mixed with amorphous carbon or carbon nanotubes were evaluated as Li-ion battery anodes. Carbon coating of the silicon nanowires using the pyrolysis of sugar was found to be crucial for making good electronic contact to the material. Using multiwalled carbon nanotubes as the conducting additive was found to be more effective for obtaining good cycling behavior than using amorphous carbon. Reversible capacities of 1500 mAh/g were observed for 30 cycles.

Microbial mediation of biogeochemical cycles revealed by simulation of global changes with soil transplant and cropping

PubMed Central

Zhao, Mengxin; Xue, Kai; Wang, Feng; Liu, Shanshan; Bai, Shijie; Sun, Bo; Zhou, Jizhong; Yang, Yunfeng

2014-01-01

Despite microbes' key roles in driving biogeochemical cycles, the mechanism of microbe-mediated feedbacks to global changes remains elusive. Recently, soil transplant has been successfully established as a proxy to simulate climate changes, as the current trend of global warming coherently causes range shifts toward higher latitudes. Four years after southward soil transplant over large transects in China, we found that microbial functional diversity was increased, in addition to concurrent changes in microbial biomass, soil nutrient content and functional processes involved in the nitrogen cycle. However, soil transplant effects could be overridden by maize cropping, which was attributed to a negative interaction. Strikingly, abundances of nitrogen and carbon cycle genes were increased by these field experiments simulating global change, coinciding with higher soil nitrification potential and carbon dioxide (CO2) efflux. Further investigation revealed strong correlations between carbon cycle genes and CO2 efflux in bare soil but not cropped soil, and between nitrogen cycle genes and nitrification. These findings suggest that changes of soil carbon and nitrogen cycles by soil transplant and cropping were predictable by measuring microbial functional potentials, contributing to a better mechanistic understanding of these soil functional processes and suggesting a potential to incorporate microbial communities in greenhouse gas emission modeling. PMID:24694714

The Bern Simple Climate Model (BernSCM) v1.0: an extensible and fully documented open-source re-implementation of the Bern reduced-form model for global carbon cycle-climate simulations

NASA Astrophysics Data System (ADS)

Strassmann, Kuno M.; Joos, Fortunat

2018-05-01

The Bern Simple Climate Model (BernSCM) is a free open-source re-implementation of a reduced-form carbon cycle-climate model which has been used widely in previous scientific work and IPCC assessments. BernSCM represents the carbon cycle and climate system with a small set of equations for the heat and carbon budget, the parametrization of major nonlinearities, and the substitution of complex component systems with impulse response functions (IRFs). The IRF approach allows cost-efficient yet accurate substitution of detailed parent models of climate system components with near-linear behavior. Illustrative simulations of scenarios from previous multimodel studies show that BernSCM is broadly representative of the range of the climate-carbon cycle response simulated by more complex and detailed models. Model code (in Fortran) was written from scratch with transparency and extensibility in mind, and is provided open source. BernSCM makes scientifically sound carbon cycle-climate modeling available for many applications. Supporting up to decadal time steps with high accuracy, it is suitable for studies with high computational load and for coupling with integrated assessment models (IAMs), for example. Further applications include climate risk assessment in a business, public, or educational context and the estimation of CO2 and climate benefits of emission mitigation options.

Centrifugally-spun carbon microfibers and porous carbon microfibers as anode materials for sodium-ion batteries

NASA Astrophysics Data System (ADS)

Dirican, Mahmut; Zhang, Xiangwu

2016-09-01

Natural abundance and low cost of sodium resources bring forward the sodium-ion batteries as a promising alternative to widely-used lithium-ion batteries. However, insufficient energy density and low cycling stability of current sodium-ion batteries hinder their practical use for next-generation smart power grid and stationary storage applications. Electrospun carbon microfibers have recently been introduced as a high-performance anode material for sodium-ion batteries. However, electrospinning is not feasible for mass production of carbon microfibers due to its complex processing condition, low production rate and high cost. Herein, we report centrifugal spinning, a high-rate and low-cost microfiber production method, as an alternative approach to electrospinning for carbon microfiber production and introduce centrifugally-spun carbon microfibers (CMFs) and porous carbon microfibers (PCMFs) as anode materials for sodium-ion batteries. Electrochemical performance results indicated that the highly porous nature of centrifugally-spun PCMFs led to increased Na+ storage capacity and improved cycling stability. The reversible capacity of centrifugally-spun PCMF anodes at the 200th cycle was 242 mAh g-1, which was much higher than that of centrifugally-spun CMFs (143 mAh g-1). The capacity retention and coulombic efficiency of the centrifugally-spun PCMF anodes were 89.0% and 99.9%, respectively, even at the 200th cycle.

Biogeochemical Cycling of Methane in the Proterozoic and Its Role in the Carbon Isotope Budget

NASA Astrophysics Data System (ADS)

Schrag, D. P.; Laakso, T.

2016-12-01

Various studies have proposed that the biogeochemical cycle of methane has played an important role throughout Earth history, both in contributing to greenhouse stability of climate in the Archean and producing carbon isotope variations and climate fluctuations in the Proterozoic and Phanerozoic. Using a simple box model that couples the geochemical cycles on carbon, oxygen, hydrogen, iron, and sulfur, combined with recent studies of methane cycling in anoxic environments, we reexamine the role of methane in both the Archean and Proterozoic, focusing on methane's role in the carbon isotope budget. We find that methane plays a much more modest role at all times of relative anoxia in the deep ocean, which requires an alternative explanation for the carbon isotope record, in particular the "boring billion" during the Mesoproterozoic. In particular, the high burial efficiency driven by lower oxygen levels drives primary production to much lower levels than has been previously described, resulting in relatively little organic matter available for methanogenesis. In addition, the anoxia in deep water results in a reduced role for methanotrophy at these times, and therefore a change in the mechanisms for production of authigenic carbonate, which may have played a significant role in the carbon isotope budget.

Carbon and nitrogen isotope variations in tree-rings as records of perturbations in regional carbon and nitrogen cycles.

PubMed

Bukata, Andrew R; Kyser, T Kurtis

2007-02-15

Increasing anthropogenic pollution from urban centers and fossil fuel combustion can impact the carbon and nitrogen cycles in forests. To assess the impact of twentieth century anthropogenic pollution on forested system carbon and nitrogen cycles, variations in the carbon and nitrogen isotopic compositions of tree-rings were measured. Individual annual growth rings in trees from six sites across Ontario and one in New Brunswick, Canada were used to develop site chronologies of tree-ring delta 15N and delta 13C values. Tree-ring 615N values were approximately 0.5% per hundred higher and correlated with contemporaneous foliar samples from the same tree, but not with delta 15N values of soil samples. Temporal trends in carbon and nitrogen isotopic compositions of these tree-rings are consistent with increasing anthropogenic influence on both the carbon and nitrogen cycles since 1945. Tree-ring delta 13C values and delta 15N values are correlated at both remote and urban-proximal sites, with delta 15N values decreasing since 1945 and converging on 1% per hundred at urban-proximal sites and decreasing but not converging on a single delta 15N value in remote sites. These results indicate that temporal trends in tree-ring nitrogen and carbon isotopic compositions record the regional extent of pollution.

A Tunable Molten-Salt Route for Scalable Synthesis of Ultrathin Amorphous Carbon Nanosheets as High-Performance Anode Materials for Lithium-Ion Batteries.

PubMed

Wang, Yixian; Tian, Wei; Wang, Luhai; Zhang, Haoran; Liu, Jialiang; Peng, Tingyue; Pan, Lei; Wang, Xiaobo; Wu, Mingbo

2018-02-14

Amorphous carbon is regarded as a promising alternative to commercial graphite as the lithium-ion battery anode due to its capability to reversibly store more lithium ions. However, the structural disorder with a large number of defects can lead to low electrical conductivity of the amorphous carbon, thus limiting its application for high power output. Herein, ultrathin amorphous carbon nanosheets were prepared from petroleum asphalt through tuning the carbonization temperature in a molten-salt medium. The amorphous nanostructure with expanded carbon interlayer spacing can provide substantial active sites for lithium storage, while the two-dimensional (2D) morphology can facilitate fast electrical conductivity. As a result, the electrodes deliver a high reversible capacity, outstanding rate capability, and superior cycling performance (579 and 396 mAh g -1 at 2 and 5 A g -1 after 900 cycles). Furthermore, full cells consisting of the carbon anodes coupled with LiMn 2 O 4 cathodes exhibit high specific capacity (608 mAh g -1 at 50 mA g -1 ) and impressive cycling stability with slow capacity loss (0.16% per cycle at 200 mA g -1 ). The present study not only paves the way for industrial-scale synthesis of advanced carbon materials for lithium-ion batteries but also deepens the fundamental understanding of the intrinsic mechanism of the molten-salt method.

Changes in the carbon cycle of northern Eurasia simulated by process models

NASA Astrophysics Data System (ADS)

Rawlins, M. A.

2013-12-01

Pronounced warming across the northern high latitudes is impacting water and carbon cycles and raising concern over possible feedbacks to global climate. Recent model studied point toward a weakening of the terrestrial land carbon sink across the northern high latitudes, one notable manifestation of a warming Arctic. We explore links between regional climate and the carbon cycle using data from models participating in the Vulnerability of Permafrost Carbon Research Coordination Network (RCN). The domain of interest is the drainage basin within the Northern Eurasia Earth Science Partnership Initiative (NEESPI) region. Model outputs examined include gross primary production (GPP), heterotrophic respiration (RH), net ecosystem exchange (NEE), and total soil carbon storage. Mean flux budgets and their changes over the period 1960-2009 are calculated from the model estimates for the entire NEESPI region and for each major land cover category within the region. Use of an independent model, which captures well the spatial pattern in soil freeze/thaw dynamics, indicates that the reduction in permafrost extent over the NEESPI basin was 4-6% over recent decades. Modeled influences of permafrost thaw on the region's water and carbon cycles are evaluated in the context of recent measurements. Estimates of the flux of CO2 due to fire are also examined in order to better understand how these disturbances are altering regional carbon sink/source dynamics.

Polydopamine-coated, nitrogen-doped, hollow carbon-sulfur double-layered core-shell structure for improving lithium-sulfur batteries.

PubMed

Zhou, Weidong; Xiao, Xingcheng; Cai, Mei; Yang, Li

2014-09-10

To better confine the sulfur/polysulfides in the electrode of lithium-sulfur (Li/S) batteries and improve the cycling stability, we developed a double-layered core-shell structure of polymer-coated carbon-sulfur. Carbon-sulfur was first prepared through the impregnation of sulfur into hollow carbon spheres under heat treatment, followed by a coating polymerization to give a double-layered core-shell structure. From the study of scanning transmission electron microscopy (STEM) images, we demonstrated that the sulfur not only successfully penetrated through the porous carbon shell but also aggregated along the inner wall of the carbon shell, which, for the first time, provided visible and convincing evidence that sulfur preferred diffusing into the hollow carbon rather than aggregating in/on the porous wall of the carbon. Taking advantage of this structure, a stable capacity of 900 mA h g(-1) at 0.2 C after 150 cycles and 630 mA h g(-1) at 0.6 C after 600 cycles could be obtained in Li/S batteries. We also demonstrated the feasibility of full cells using the sulfur electrodes to couple with the silicon film electrodes, which exhibited significantly improved cycling stability and efficiency. The remarkable electrochemical performance could be attributed to the desirable confinement of sulfur through the unique double-layered core-shell architectures.

Nitrogen doped carbon derived from polyimide/multiwall carbon nanotube composites for high performance flexible all-solid-state supercapacitors

NASA Astrophysics Data System (ADS)

Kim, Dae Kyom; Kim, Nam Dong; Park, Seung-Keun; Seong, Kwang-dong; Hwang, Minsik; You, Nam-Ho; Piao, Yuanzhe

2018-03-01

Flexible all-solid-state supercapacitors are desirable as potential energy storage systems for wearable technologies. Herein, we synthesize aminophenyl multiwall carbon nanotube (AP-MWCNT) grafted polyimide precursor by in situ polymerization method as a nitrogen-doped carbon precursor. Flexible supercapacitor electrodes are fabricated via a coating of carbon precursor on carbon cloth surface and carbonization at high temperature directly. The as-obtained electrodes, which can be directly used without any binders or additives, can deliver a high specific capacitance of 333.4 F g-1 at 1 A g-1 (based on active material mass) and excellent cycle stability with 103% capacitance retention after 10,000 cycles in a three-electrode system. The flexible all-solid-state supercapacitor device exhibits a high volumetric capacitance of 3.88 F cm-3 at a current density of 0.02 mA cm-3. And also the device can deliver a maximum volumetric energy density of 0.50 mWh cm-3 and presents good cycling stability with 85.3% capacitance retention after 10,000 cycles. This device cell can not only show extraordinary mechanical flexibilities allowing folding, twisting, and rolling but also demonstrate remarkable stable electrochemical performances under their forms. This work provides a novel approach to obtain carbon textile-based flexible supercapacitors with high electrochemical performance and mechanical flexibility.

One-pot synthesis of carbon-coated nanosized LiTi2(PO4)3 as anode materials for aqueous lithium ion batteries

NASA Astrophysics Data System (ADS)

Liu, Zhantao; Qin, Xusong; Xu, Hui; Chen, Guohua

2015-10-01

In this study, a one-pot sintering process incorporating sol-gel preparation route and in-situ carbon coating was proposed for the synthesis of carbon-coated nanosized LiTi2(PO4)3. Experimental results show that the prepared LiTi2(PO4)3 particles are of high crystallinity and well-coated by turbostratic carbon. Attributed to nanosized particles and enhanced conductivity provided by turbostratic carbon coating, the carbon-coated LiTi2(PO4)3 showed high rate performance and good cycling life in aqueous electrolyte. Particularly, the carbon-coated LiTi2(PO4)3 exhibited initial specific capacities of 103 and 89 mAh g-1, and retained 80.6% and 97% of the initial capacities after 120 cycles at 1C and 10C in aqueous electrolyte, respectively. The high rate performance and good cycling life of carbon-coated LiTi2(PO4)3 in aqueous electrolyte reveal its potential as negative electrode in aqueous lithium-ion batteries for electric vehicles and industrial-scale energy storage systems.

Facile Synthesis of Coaxial CNTs/MnOx-Carbon Hybrid Nanofibers and Their Greatly Enhanced Lithium Storage Performance.

PubMed

Yang, Zunxian; Lv, Jun; Pang, Haidong; Yan, Wenhuan; Qian, Kun; Guo, Tailiang; Guo, Zaiping

2015-12-01

Carbon nanotubes (CNTs)/MnOx-Carbon hybrid nanofibers have been successfully synthesized by the combination of a liquid chemical redox reaction (LCRR) and a subsequent carbonization heat treatment. The nanostructures exhibit a unique one-dimensional core/shell architecture, with one-dimensional CNTs encapsulated inside and a MnOx-carbon composite nanoparticle layer on the outside. The particular porous characteristics with many meso/micro holes/pores, the highly conductive one-dimensional CNT core, as well as the encapsulating carbon matrix on the outside of the MnOx nanoparticles, lead to excellent electrochemical performance of the electrode. The CNTs/MnOx-Carbon hybrid nanofibers exhibit a high initial reversible capacity of 762.9 mAhg(-1), a high reversible specific capacity of 560.5 mAhg(-1) after 100 cycles, and excellent cycling stability and rate capability, with specific capacity of 396.2 mAhg(-1) when cycled at the current density of 1000 mAg(-1), indicating that the CNTs/MnOx-Carbon hybrid nanofibers are a promising anode candidate for Li-ion batteries.

Facile Synthesis of Coaxial CNTs/MnOx-Carbon Hybrid Nanofibers and Their Greatly Enhanced Lithium Storage Performance

PubMed Central

Yang, Zunxian; Lv, Jun; Pang, Haidong; Yan, Wenhuan; Qian, Kun; Guo, Tailiang; Guo, Zaiping

2015-01-01

Carbon nanotubes (CNTs)/MnOx-Carbon hybrid nanofibers have been successfully synthesized by the combination of a liquid chemical redox reaction (LCRR) and a subsequent carbonization heat treatment. The nanostructures exhibit a unique one-dimensional core/shell architecture, with one-dimensional CNTs encapsulated inside and a MnOx-carbon composite nanoparticle layer on the outside. The particular porous characteristics with many meso/micro holes/pores, the highly conductive one-dimensional CNT core, as well as the encapsulating carbon matrix on the outside of the MnOx nanoparticles, lead to excellent electrochemical performance of the electrode. The CNTs/MnOx-Carbon hybrid nanofibers exhibit a high initial reversible capacity of 762.9 mAhg−1, a high reversible specific capacity of 560.5 mAhg−1 after 100 cycles, and excellent cycling stability and rate capability, with specific capacity of 396.2 mAhg−1 when cycled at the current density of 1000 mAg−1, indicating that the CNTs/MnOx-Carbon hybrid nanofibers are a promising anode candidate for Li-ion batteries. PMID:26621615

Effects of biotic disturbances on forest carbon cycling in the United States and Canada

Treesearch

Jeffrey A. Hicke; Craig D. Allen; Ankur R. Desai; Michael C. Dietze; Ronald J. Hall; Edward H. Hogg; Daniel M. Kashian; David Moore; Kenneth F. Raffa; Rona N. Sturrock; James Vogelmann

2011-01-01

Forest insects and pathogens are major disturbance agents that have affected millions of hectares in North America in recent decades, implying significant impacts to the carbon (C) cycle. Here, we review and synthesize published studies of the effects of biotic disturbances on forest C cycling in the United States and Canada. Primary productivity in stands was reduced...

An Analytical Framework for the Steady State Impact of Carbonate Compensation on Atmospheric CO2

NASA Astrophysics Data System (ADS)

Omta, Anne Willem; Ferrari, Raffaele; McGee, David

2018-04-01

The deep-ocean carbonate ion concentration impacts the fraction of the marine calcium carbonate production that is buried in sediments. This gives rise to the carbonate compensation feedback, which is thought to restore the deep-ocean carbonate ion concentration on multimillennial timescales. We formulate an analytical framework to investigate the impact of carbonate compensation under various changes in the carbon cycle relevant for anthropogenic change and glacial cycles. Using this framework, we show that carbonate compensation amplifies by 15-20% changes in atmospheric CO2 resulting from a redistribution of carbon between the atmosphere and ocean (e.g., due to changes in temperature, salinity, or nutrient utilization). A counterintuitive result emerges when the impact of organic matter burial in the ocean is examined. The organic matter burial first leads to a slight decrease in atmospheric CO2 and an increase in the deep-ocean carbonate ion concentration. Subsequently, enhanced calcium carbonate burial leads to outgassing of carbon from the ocean to the atmosphere, which is quantified by our framework. Results from simulations with a multibox model including the minor acids and bases important for the ocean-atmosphere exchange of carbon are consistent with our analytical predictions. We discuss the potential role of carbonate compensation in glacial-interglacial cycles as an example of how our theoretical framework may be applied.

Normalized algorithm for mapping and dating forest disturbances and regrowth for the United States

Treesearch

Liming He; Jing M. Chen; Shaoliang Zhang; Gustavo Gomez; Yude Pan; Kevin McCullough; Richard Birdsey; Jeffrey G. Masek

2011-01-01

Forest disturbances such as harvesting, wildfire and insect infestation are critical ecosystem processes affecting the carbon cycle. Because carbon dynamics are related to time since disturbance, forest stand age that can be used as a surrogate for major clear-cut/fire disturbance information has recently been recognized as an important input to forest carbon cycle...

Land use change effects on forest carbon cycling throughout the southern United States

Treesearch

Peter B. Woodbury; Linda S. Heath; James E. Smith

2006-01-01

We modeled the effects of afforestation and deforestation on carbon cycling in forest floor and soil from 1900 to 2050 throughout 13 states in the southern United States. The model uses historical data on gross (two-way) transitions between forest, pasture, plowed agriculture, and urban lands along with equations describing changes in carbon over many decades for each...

Carbon Cathodes in Rechargeable Lithium-Oxygen Batteries Based on Double-Lithium-Salt Electrolytes.

PubMed

Yoo, Eunjoo; Zhou, Haoshen

2016-06-08

The use of carbon materials as air electrodes in lithium-oxygen (Li-O2 ) batteries is known to be advantageous owing to their good conductivity and because they offer sites suitable for the reversible electrode reactions. However, the exact influence of carbon materials on the electrochemical performance of Li-O2 batteries is not clear. In this study the electrochemical performance of four different types of carbon materials (multiwalled carbon nanotubes (MWCNTs), CMK-3, graphene nanosheets (GNSs), and Ketjen Black (KB)) as air electrodes is examined. We find that a Li-O2 cell based on an electrode of multiwalled carbon nanotubes (MWCNTs) demonstrates good rate performance and cycle stability, when using LiNO3 -LiTFSI/DMSO as electrolyte. Li-O2 cells based on such MWCNT electrodes, with a cut-off capacity of 1000 mAh g(-1) at 500 mA g(-1) , can undergo around 90 cycles without obvious losses of capacity. Even when the discharge depth is increased to 2000 mA h g(-1) , stable cycling is maintained for 45 cycles at a charge potential below 4.0 V. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Evidence for iron-sulfate coupling in salt marsh sediments

NASA Astrophysics Data System (ADS)

Mills, Jennifer; Antler, Gilad; Turchyn, Alexandra

2014-05-01

Organic carbon burial in shallow marine sediments represents an important net sink in the global carbon cycle. Microbially mediated oxidation of organic matter in oxic, suboxic, and anoxic sediments however, prevents the ultimate burial of organic carbon and its removal from the surface of the planet. Although the subsurface transformations of organic carbon have been studied extensively, an enigmatic question remains: when organic matter is deposited, what determines whether it will be buried, reoxidized, or undergo methanogenesis? One hypothesis is that the sulfur cycle, due to the abundance of sulfate in many surface environments, dominates the subsurface oxidation or other fate of organic carbon. However, it has also been suggested that iron may in turn play a key role in determining the behavior of the sulfur cycle. To better understand the controls on these processes, we are using stable isotope and geochemical techniques to explore the microbially mediated oxidation of organic carbon in salt marsh sediments in North Norfolk, UK. In these sediments there is a high supply of organic carbon, iron, and sulfate (from diurnal tidal cycles). Thus these environments may provide insight into the nature of interactions between the carbon, iron, and sulfur cycles. A series of sampling missions was undertaken in the autumn and winter of 2013-2014. In subsurface fluid samples we observe very high ferrous iron concentrations (>1mM), indicative of extended regions of iron reduction (to over 30cm depth). Within these zones of iron reduction we would predict no sulfate reduction, and as expected δ34Ssulfate remains unchanged with depth. However, δ18Osulfate exhibits significant enrichments of up to 5 permil. This decoupling in the sulfur and oxygen isotopes of sulfate is suggestive of a sulfate recycling process in which sulfate is reduced to an intermediate sulfur species and subsequently reoxidized to sulfate. Taken together, these data suggest that microbial assemblages in these salt marsh sediments facilitate a cryptic cycling of sulfur, potentially mediated by iron species in the zone of iron reduction.

Effects of climate extremes on the terrestrial carbon cycle: concepts, processes and potential future impacts

PubMed Central

Frank, Dorothea; Reichstein, Markus; Bahn, Michael; Thonicke, Kirsten; Frank, David; Mahecha, Miguel D; Smith, Pete; van der Velde, Marijn; Vicca, Sara; Babst, Flurin; Beer, Christian; Buchmann, Nina; Canadell, Josep G; Ciais, Philippe; Cramer, Wolfgang; Ibrom, Andreas; Miglietta, Franco; Poulter, Ben; Rammig, Anja; Seneviratne, Sonia I; Walz, Ariane; Wattenbach, Martin; Zavala, Miguel A; Zscheischler, Jakob

2015-01-01

Extreme droughts, heat waves, frosts, precipitation, wind storms and other climate extremes may impact the structure, composition and functioning of terrestrial ecosystems, and thus carbon cycling and its feedbacks to the climate system. Yet, the interconnected avenues through which climate extremes drive ecological and physiological processes and alter the carbon balance are poorly understood. Here, we review the literature on carbon cycle relevant responses of ecosystems to extreme climatic events. Given that impacts of climate extremes are considered disturbances, we assume the respective general disturbance-induced mechanisms and processes to also operate in an extreme context. The paucity of well-defined studies currently renders a quantitative meta-analysis impossible, but permits us to develop a deductive framework for identifying the main mechanisms (and coupling thereof) through which climate extremes may act on the carbon cycle. We find that ecosystem responses can exceed the duration of the climate impacts via lagged effects on the carbon cycle. The expected regional impacts of future climate extremes will depend on changes in the probability and severity of their occurrence, on the compound effects and timing of different climate extremes, and on the vulnerability of each land-cover type modulated by management. Although processes and sensitivities differ among biomes, based on expert opinion, we expect forests to exhibit the largest net effect of extremes due to their large carbon pools and fluxes, potentially large indirect and lagged impacts, and long recovery time to regain previous stocks. At the global scale, we presume that droughts have the strongest and most widespread effects on terrestrial carbon cycling. Comparing impacts of climate extremes identified via remote sensing vs. ground-based observational case studies reveals that many regions in the (sub-)tropics are understudied. Hence, regional investigations are needed to allow a global upscaling of the impacts of climate extremes on global carbon–climate feedbacks. PMID:25752680

Sensitivity of Global Terrestrial Gross Primary Production to Hydrologic States Simulated by the Community Land Model Using Two Runoff Parameterizations

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

Lei, Huimin; Huang, Maoyi; Leung, Lai-Yung R.

2014-09-01

The terrestrial water and carbon cycles interact strongly at various spatio-temporal scales. To elucidate how hydrologic processes may influence carbon cycle processes, differences in terrestrial carbon cycle simulations induced by structural differences in two runoff generation schemes were investigated using the Community Land Model 4 (CLM4). Simulations were performed with runoff generation using the default TOPMODEL-based and the Variable Infiltration Capacity (VIC) model approaches under the same experimental protocol. The comparisons showed that differences in the simulated gross primary production (GPP) are mainly attributed to differences in the simulated leaf area index (LAI) rather than soil moisture availability. More specifically,more » differences in runoff simulations can influence LAI through changes in soil moisture, soil temperature, and their seasonality that affect the onset of the growing season and the subsequent dynamic feedbacks between terrestrial water, energy, and carbon cycles. As a result of a relative difference of 36% in global mean total runoff between the two models and subsequent changes in soil moisture, soil temperature, and LAI, the simulated global mean GPP differs by 20.4%. However, the relative difference in the global mean net ecosystem exchange between the two models is small (2.1%) due to competing effects on total mean ecosystem respiration and other fluxes, although large regional differences can still be found. Our study highlights the significant interactions among the water, energy, and carbon cycles and the need for reducing uncertainty in the hydrologic parameterization of land surface models to better constrain carbon cycle modeling.« less

Incorporating phosphorus cycling into global modeling efforts: a worthwhile, tractable endeavor.

PubMed

Reed, Sasha C; Yang, Xiaojuan; Thornton, Peter E

2015-10-01

324 I. 324 II. 325 III. 326 IV. 327 328 References 328 SUMMARY: Myriad field, laboratory, and modeling studies show that nutrient availability plays a fundamental role in regulating CO2 exchange between the Earth's biosphere and atmosphere, and in determining how carbon pools and fluxes respond to climatic change. Accordingly, global models that incorporate coupled climate-carbon cycle feedbacks made a significant advance with the introduction of a prognostic nitrogen cycle. Here we propose that incorporating phosphorus cycling represents an important next step in coupled climate-carbon cycling model development, particularly for lowland tropical forests where phosphorus availability is often presumed to limit primary production. We highlight challenges to including phosphorus in modeling efforts and provide suggestions for how to move forward. No claim to original US government works New Phytologist © 2015 New Phytologist Trust.

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

Bishop, James K.B.

Prediction of the substantial biologically mediated carbon flows in a rapidly changing and acidifying ocean requires model simulations informed by observations of key carbon cycle processes on the appropriate space and time scales. From 2000 to 2004, the National Oceanographic Partnership Program (NOPP) supported the development of the first low-cost fully-autonomous ocean profiling Carbon Explorers that demonstrated that year-round real-time observations of particulate organic carbon (POC) concentration and sedimentation could be achieved in the world's ocean. NOPP also initiated the development of a sensor for particulate inorganic carbon (PIC) suitable for operational deployment across all oceanographic platforms. As a result,more » PIC profile characterization that once required shipboard sample collection and shipboard or shore based laboratory analysis, is now possible to full ocean depth in real time using a 0.2W sensor operating at 24 Hz. NOPP developments further spawned US DOE support to develop the Carbon Flux Explorer, a free-vehicle capable of following hourly variations of particulate inorganic and organic carbon sedimentation from near surface to kilometer depths for seasons to years and capable of relaying contemporaneous observations via satellite. We have demonstrated the feasibility of real time - low cost carbon observations which are of fundamental value to carbon prediction and when further developed, will lead to a fully enhanced global carbon observatory capable of real time assessment of the ocean carbon sink, a needed constraint for assessment of carbon management policies on a global scale.« less

On the linkages between the global carbon-nitrogen-phosphorus cycles

NASA Astrophysics Data System (ADS)

Tanaka, Katsumasa; Mackenzie, Fred; Bouchez, Julien; Knutti, Reto

2013-04-01

State-of-the-art earth system models used for long-term climate projections are becoming ever more complex in terms of not only spatial resolution but also the number of processes. Biogeochemical processes are beginning to be incorporated into these models. The motivation of this study is to quantify how climate projections are influenced by biogeochemical feedbacks. In the climate modeling community, it is virtually accepted that climate-Carbon (C) cycle feedbacks accelerate the future warming (Cox et al. 2000; Friedlingstein et al. 2006). It has been demonstrated that the Nitrogen (N) cycle suppresses climate-C cycle feedbacks (Thornton et al. 2009). On the contrary, biogeochemical studies show that the coupled C-N-Phosphorus (P) cycles are intimately interlinked via biosphere and the N-P cycles amplify C cycle feedbacks (Ver et al. 1999). The question as to whether the N-P cycles enhance or attenuate C cycle feedbacks is debated and has a significant implication for projections of future climate. We delve into this problem by using the Terrestrial-Ocean-aTmosphere Ecosystem Model 3 (TOTEM3), a globally-aggregated C-N-P cycle box model. TOTEM3 is a process-based model that describes the biogeochemical reactions and physical transports involving these elements in the four domains of the Earth system: land, atmosphere, coastal ocean, and open ocean. TOTEM3 is a successor of earlier TOTEM models (Ver et al. 1999; Mackenzie et al. 2011). In our presentation, we provide an overview of fundamental features and behaviors of TOTEM3 such as the mass balance at the steady state and the relaxation time scales to various types of perturbation. We also show preliminary results to investigate how the N-P cycles influence the behavior of the C cycle. References Cox PM, Betts RA, Jones CD, Spall SA, Totterdell IJ (2000) Acceleration of global warming due to carbon-cycle feedbacks in a coupled climate model. Nature, 408, 184-187. Friedlingstein P, Cox P, Betts R, Bopp L, von Bloh W, Brovkin V, Cadule P, Doney S, Eby M, Fung I, Bala G, John J, Jones C, Joos F, Kato T, Kawamiya M, Knorr W, Lindsay K, Matthews HD, Raddatz T, Rayner P, Reick C, Roeckner E, Schnitzler KG, Schnur R, Strassmann K, Weaver AJ, Yoshikawa C, Zeng N (2006) Climate-Carbon Cycle Feedback Analysis: Results from the C4MIP Model Intercomparison. Journal of Climate, 19, 3337-3353. Mackenzie FT, De Carlo EH, Lerman A (2011) Coupled C, N, P, and O biogeochemical cycling at the land-ocean interface. In: Wolanski E, McLusky DS (eds) Treatise on Estuarine and Coastal Science, vol 5. Academic Press, Waltham, pp 317-342. Thornton PE, Doney SC, Lindsay K, Moore JK, Mahowald N, Randerson JT, Fung I, Lamarque JF, Feddema JJ, Lee YH (2009) Carbon-nitrogen interactions regulate climate-carbon cycle feedbacks: results from an atmosphere-ocean general circulation model. Biogeosciences, 6, 2099-2120. Ver LMB, Mackenzie FT, Lerman A (1999) Biogeochemical responses of the carbon cycle to natural and human perturbations: Past, present, and future. American Journal of Science, 299, 762-801.

Exploring Research Contributions of the North American Carbon Program using Google Earth and Google Map

NASA Astrophysics Data System (ADS)

Griffith, P. C.; Wilcox, L. E.; Morrell, A.

2009-12-01

The central objective of the North American Carbon Program (NACP), a core element of the US Global Change Research Program, is to quantify the sources and sinks of carbon dioxide, carbon monoxide, and methane in North America and adjacent ocean regions. The NACP consists of a wide range of investigators at universities and federal research centers. Although many of these investigators have worked together in the past, many have had few prior interactions and may not know of similar work within knowledge domains, much less across the diversity of environments and scientific approaches in the Program. Coordinating interactions and sharing data are major challenges in conducting NACP. The Google Earth and Google Map Collections on the NACP website (www.nacarbon.org) provide a geographical view of the research products contributed by each core and affiliated NACP project. Other relevant data sources (e.g. AERONET, LVIS) can also be browsed in spatial context with NACP contributions. Each contribution links to project-oriented metadata, or “project profiles”, that provide a greater understanding of the scientific and social context of each dataset and are an important means of communicating within the NACP and to the larger carbon cycle science community. Project profiles store information such as a project's title, leaders, participants, an abstract, keywords, funding agencies, associated intensive campaigns, expected data products, data needs, publications, and URLs to associated data centers, datasets, and metadata. Data products are research contributions that include biometric inventories, flux tower estimates, remote sensing land cover products, tools, services, and model inputs / outputs. Project leaders have been asked to identify these contributions to the site level whenever possible, either through simple latitude/longitude pair, or by uploading a KML, KMZ, or shape file. Project leaders may select custom icons to graphically categorize their contributions; for example, a ship for oceanographic samples, a tower for tower measurements. After post-processing, research contributions are added to the NACP Google Earth and Google Map Collection to facilitate discovery and use in synthesis activities of the Program.

A Natural Light/Dark Cycle Regulation of Carbon-Nitrogen Metabolism and Gene Expression in Rice Shoots.

PubMed

Li, Haixing; Liang, Zhijun; Ding, Guangda; Shi, Lei; Xu, Fangsen; Cai, Hongmei

2016-01-01

Light and temperature are two particularly important environmental cues for plant survival. Carbon and nitrogen are two essential macronutrients required for plant growth and development, and cellular carbon and nitrogen metabolism must be tightly coordinated. In order to understand how the natural light/dark cycle regulates carbon and nitrogen metabolism in rice plants, we analyzed the photosynthesis, key carbon-nitrogen metabolites, and enzyme activities, and differentially expressed genes and miRNAs involved in the carbon and nitrogen metabolic pathway in rice shoots at the following times: 2:00, 6:00, 10:00, 14:00, 18:00, and 22:00. Our results indicated that more CO2 was fixed into carbohydrates by a high net photosynthetic rate, respiratory rate, and stomatal conductance in the daytime. Although high levels of the nitrate reductase activity, free ammonium and carbohydrates were exhibited in the daytime, the protein synthesis was not significantly facilitated by the light and temperature. In mRNA sequencing, the carbon and nitrogen metabolism-related differentially expressed genes were obtained, which could be divided into eight groups: photosynthesis, TCA cycle, sugar transport, sugar metabolism, nitrogen transport, nitrogen reduction, amino acid metabolism, and nitrogen regulation. Additionally, a total of 78,306 alternative splicing events have been identified, which primarily belong to alternative 5' donor sites, alternative 3' acceptor sites, intron retention, and exon skipping. In sRNA sequencing, four carbon and nitrogen metabolism-related miRNAs (osa-miR1440b, osa-miR2876-5p, osa-miR1877 and osa-miR5799) were determined to be regulated by natural light/dark cycle. The expression level analysis showed that the four carbon and nitrogen metabolism-related miRNAs negatively regulated their target genes. These results may provide a good strategy to study how natural light/dark cycle regulates carbon and nitrogen metabolism to ensure plant growth and development.

Molecular Basis of Microbial One-Carbon Metabolism 2008 Gordon Research Conference (July 20-25, 2008)

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

Stephen W. Ragsdale

2009-08-12

One-carbon (C-1) compounds play a central role in microbial metabolism. C-1 compounds include methane, carbon monoxide, CO2, and methanol as well as coenzyme-bound one-carbon compounds (methyl-B12, CH3-H4folate, etc). Such compounds are of broad global importance because several C-1 compounds (e.g., CH4) are important energy sources, some (e.g., CO2 and CH4) are potent greenhouse gases, and others (e.g., CH2Cl2) are xenobiotics. They are central in pathways of energy metabolism and carbon fixation by microbes and many are of industrial interest. Research on the pathways of one-carbon metabolism has added greatly to our understanding of evolution, structural biology, enzyme mechanisms, gene regulation,more » ecology, and applied biology. The 2008 meeting will include recent important findings in the following areas: (a) genomics, metagenomics, and proteomic studies that have expanded our understanding of autotrophy and C-1 metabolism and the evolution of these pathways; (b) redox regulation of carbon cycles and the interrelationship between the carbon cycle and other biogeochemical cycles (sulfur, nitrogen, oxygen); (c) novel pathways for carbon assimilation; (d) biotechnology related to C-1 metabolism; (e) novel enzyme mechanisms including channeling of C-1 intermediates during metabolism; and (f) the relationship between metal homeostasis and the global carbon cycle. The conference has a diverse and gender-balanced slate of speakers and session leaders. The wide variety of disciplines brought to the study of C-1 metabolism make the field an excellent one in which to train young researchers.« less

Effect of Carbon Coating on Li4TiO12 of Anode Material for Hybrid Capacitor.

PubMed

Lee, Jong-Kyu; Lee, Byung-Gwan; Yoon, Jung-Rag

2015-11-01

The carbon-coated Li4Ti5O12 of anode material for hybrid capacitor was prepared by controlling carbonization time at 700 degrees C in nitrogen. With increasing of carbonization time, the discharge capacity and capacitance were decreased, while the equivalent series resistance was not changed remarkably. The rate capability and cycle performance of carbon-coated Li4Ti5O12 were larger than that of Li4Ti5O12. Carbon coating improved conductivity as well as Li-ion diffusion, and thus also resulted in good rate capabilities and cycle stability. The effects of carbon coating on the gas generation of hybrid capacitor were also discussed.

Forecasting Responses of a Northern Peatland Carbon Cycle to Elevated CO2 and a Gradient of Experimental Warming

NASA Astrophysics Data System (ADS)

Jiang, Jiang; Huang, Yuanyuan; Ma, Shuang; Stacy, Mark; Shi, Zheng; Ricciuto, Daniel M.; Hanson, Paul J.; Luo, Yiqi

2018-03-01

The ability to forecast ecological carbon cycling is imperative to land management in a world where past carbon fluxes are no longer a clear guide in the Anthropocene. However, carbon-flux forecasting has not been practiced routinely like numerical weather prediction. This study explored (1) the relative contributions of model forcing data and parameters to uncertainty in forecasting flux- versus pool-based carbon cycle variables and (2) the time points when temperature and CO2 treatments may cause statistically detectable differences in those variables. We developed an online forecasting workflow (Ecological Platform for Assimilation of Data (EcoPAD)), which facilitates iterative data-model integration. EcoPAD automates data transfer from sensor networks, data assimilation, and ecological forecasting. We used the Spruce and Peatland Responses Under Changing Experiments data collected from 2011 to 2014 to constrain the parameters in the Terrestrial Ecosystem Model, forecast carbon cycle responses to elevated CO2 and a gradient of warming from 2015 to 2024, and specify uncertainties in the model output. Our results showed that data assimilation substantially reduces forecasting uncertainties. Interestingly, we found that the stochasticity of future external forcing contributed more to the uncertainty of forecasting future dynamics of C flux-related variables than model parameters. However, the parameter uncertainty primarily contributes to the uncertainty in forecasting C pool-related response variables. Given the uncertainties in forecasting carbon fluxes and pools, our analysis showed that statistically different responses of fast-turnover pools to various CO2 and warming treatments were observed sooner than slow-turnover pools. Our study has identified the sources of uncertainties in model prediction and thus leads to improve ecological carbon cycling forecasts in the future.

Silk-regulated hierarchical hollow magnetite/carbon nanocomposite spheroids for lithium-ion battery anodes.

PubMed

Sheng, Weiqin; Zhu, Guobin; Kaplan, David L; Cao, Chuanbao; Zhu, Hesun; Lu, Qiang

2015-03-20

Hierarchical olive-like structured carbon-Fe3O4 nanocomposite particles composed of a hollow interior and a carbon coated surface are prepared by a facile, silk protein-assisted hydrothermal method. Silk nanofibers as templates and carbon precursors first regulate the formation of hollow Fe2O3 microspheres and then they are converted into carbon by a reduction process into Fe3O4. This process significantly simplifies the fabrication and carbon coating processes to form complex hollow structures. When tested as anode materials for lithium-ion batteries, these hollow carbon-coated particles exhibit high capacity (900 mAh g(-1)), excellent cycle stability (180 cycles) and rate performance due to their unique hierarchical hollow structure and carbon coating.

Spectroscopic and Photometric Properties of Carbon Stars in the Disk of the Andromeda Galaxy

NASA Astrophysics Data System (ADS)

Guhathakurta, Puragra; Toloba, E.; Guha, S.; Rushing, C.; Dorman, C.; PHAT Collaboration; SPLASH Collaboration

2013-01-01

We explore the spectroscopic properties of a couple hundred carbon stars discovered in the disk of the Andromeda galaxy (M31) in the course of the Spectroscopic and Photometric Landscape of Andromeda's Stellar Halo (SPLASH) survey. The spectra were obtained using the DEIMOS spectrograph on the Keck II 10-meter telescope. About 5000 stars were targeted for spectroscopy during observing runs in 2010 and 2011 using DEIMOS's 1200 lines/mm grating with a spectral resolving power of R ~ 5000 to 6000 and spectral coverage from 6500-9000 Angstrom. In September 2012, another 5000 stars were observed this time with the 600 lines/mm grating and R ~ 2500 and spectral coverage from 4500-9000 Angstrom. For both types of spectroscopic observations, targets were selected from the Panchromatic Hubble Andromeda Treasury (PHAT) multi-cycle treasury program with the Hubble Space Telescope. Six-filter photometry in the ultraviolet (F275W, F336W), optical (F439W, F814W), and near infrared (F110W, F160W) is available for most targets. These carbon star samples are used to constrain the intermediage-age population in M31's disk. They are also compared to spectra of previously known carbon samples in the dwarf elliptical satellites of M31, NGC 147, NGC 185, and NGC 205. The authors thank the National Science Foundation, NASA/STScI, and UCSC's Summer Internship Program for support.

Orbital pacing of carbon fluxes by a ∼9-My eccentricity cycle during the Mesozoic

PubMed Central

Martinez, Mathieu; Dera, Guillaume

2015-01-01

Eccentricity, obliquity, and precession are cyclic parameters of the Earth’s orbit whose climatic implications have been widely demonstrated on recent and short time intervals. Amplitude modulations of these parameters on million-year time scales induce ‟grand orbital cycles,” but the behavior and the paleoenvironmental consequences of these cycles remain debated for the Mesozoic owing to the chaotic diffusion of the solar system in the past. Here, we test for these cycles from the Jurassic to the Early Cretaceous by analyzing new stable isotope datasets reflecting fluctuations in the carbon cycle and seawater temperatures. Our results document a prominent cyclicity of ∼9 My in the carbon cycle paced by changes in the seasonal dynamics of hydrological processes and long-term sea level fluctuations. These paleoenvironmental changes are linked to a great eccentricity cycle consistent with astronomical solutions. The orbital forcing signal was mainly amplified by cumulative sequestration of organic matter in the boreal wetlands under greenhouse conditions. Finally, we show that the ∼9-My cycle faded during the Pliensbachian, which could either reflect major paleoenvironmental disturbances or a chaotic transition affecting this cycle. PMID:26417080

Structures of dolomite at ultrahigh pressure and their influence on the deep carbon cycle

PubMed Central

Merlini, Marco; Crichton, Wilson A.; Hanfland, Michael; Gemmi, Mauro; Müller, Harald; Kupenko, Ilya; Dubrovinsky, Leonid

2012-01-01

Carbon-bearing solids, fluids, and melts in the Earth's deep interior may play an important role in the long-term carbon cycle. Here we apply synchrotron X-ray single crystal micro-diffraction techniques to identify and characterize the high-pressure polymorphs of dolomite. Dolomite-II, observed above 17 GPa, is triclinic, and its structure is topologically related to CaCO3-II. It transforms above 35 GPa to dolomite-III, also triclinic, which features carbon in [3 + 1] coordination at the highest pressures investigated (60 GPa). The structure is therefore representative of an intermediate between the low-pressure carbonates and the predicted ultra-high pressure carbonates, with carbon in tetrahedral coordination. Dolomite-III does not decompose up to the melting point (2,600 K at 43 GPa) and its thermodynamic stability demonstrates that this complex phase can transport carbon to depths of at least up to 1,700 km. Dolomite-III, therefore, is a likely occurring phase in areas containing recycled crustal slabs, which are more oxidized and Ca-enriched than the primitive lower mantle. Indeed, these phases may play an important role as carbon carriers in the whole mantle carbon cycling. As such, they are expected to participate in the fundamental petrological processes which, through carbon-bearing fluids and carbonate melts, will return carbon back to the Earth’s surface. PMID:22869705

Floodplain soil organic carbon storage in the central Yukon River Basin

NASA Astrophysics Data System (ADS)

Lininger, K.; Wohl, E.

2017-12-01

As rivers transport sediment, organic matter, and large wood, they can deposit those materials in their floodplains, storing carbon. One aspect of the carbon cycle that isn't well understood is how much carbon is stored in rivers and floodplains. There may be more carbon in rivers and floodplains than previously thought. This is important for accounting for all aspects of the carbon cycle, which is the movement of carbon among the land, ocean, and atmosphere. We are quantifying that storage in high latitude floodplains through fieldwork along five rivers in the central Yukon River Basin within the Yukon Flats National Wildlife Refuge in interior Alaska. We find that the geomorphic environment and geomorphic characteristics of rivers influence the spatial distribution of carbon on the landscape, and that floodplains may be disproportionally important for carbon storage compared to other areas. Our study area contains discontinuous permafrost, which is soil that is perennially frozen, and is warming quickly due to climate change, as in other high latitude regions. The large amount of carbon stored in the subsurface and in permafrost in the high latitudes highlights the importance of understanding where carbon is stored within rivers and floodplains in these regions and how long that carbon remains in storage. Our research helps inform how river systems influence the carbon cycle in a region undergoing rapid change.

Reservoirs as hotspots of fluvial carbon cycling in peatland catchments.

PubMed

Stimson, A G; Allott, T E H; Boult, S; Evans, M G

2017-02-15

Inland water bodies are recognised as dynamic sites of carbon processing, and lakes and reservoirs draining peatland soils are particularly important, due to the potential for high carbon inputs combined with long water residence times. A carbon budget is presented here for a water supply reservoir (catchment area~9km 2 ) draining an area of heavily eroded upland peat in the South Pennines, UK. It encompasses a two year dataset and quantifies reservoir dissolved organic carbon (DOC), particulate organic carbon (POC) and aqueous carbon dioxide (CO 2 (aq)) inputs and outputs. The budget shows the reservoir to be a hotspot of fluvial carbon cycling, as with high levels of POC influx it acts as a net sink of fluvial carbon and has the potential for significant gaseous carbon export. The reservoir alternates between acting as a producer and consumer of DOC (a pattern linked to rainfall and temperature) which provides evidence for transformations between different carbon species. In particular, the budget data accompanied by 14 C (radiocarbon) analyses provide evidence that POC-DOC transformations are a key process, occurring at rates which could represent at least ~10% of the fluvial carbon sink. To enable informed catchment management further research is needed to produce carbon cycle models more applicable to these environments, and on the implications of high POC levels for DOC composition. Copyright © 2016 Elsevier B.V. All rights reserved.

Compiled records of carbon isotopes in atmospheric CO2 for historical simulations in CMIP6

NASA Astrophysics Data System (ADS)

Graven, Heather; Allison, Colin E.; Etheridge, David M.; Hammer, Samuel; Keeling, Ralph F.; Levin, Ingeborg; Meijer, Harro A. J.; Rubino, Mauro; Tans, Pieter P.; Trudinger, Cathy M.; Vaughn, Bruce H.; White, James W. C.

2017-12-01

The isotopic composition of carbon (Δ14C and δ13C) in atmospheric CO2 and in oceanic and terrestrial carbon reservoirs is influenced by anthropogenic emissions and by natural carbon exchanges, which can respond to and drive changes in climate. Simulations of 14C and 13C in the ocean and terrestrial components of Earth system models (ESMs) present opportunities for model evaluation and for investigation of carbon cycling, including anthropogenic CO2 emissions and uptake. The use of carbon isotopes in novel evaluation of the ESMs' component ocean and terrestrial biosphere models and in new analyses of historical changes may improve predictions of future changes in the carbon cycle and climate system. We compile existing data to produce records of Δ14C and δ13C in atmospheric CO2 for the historical period 1850-2015. The primary motivation for this compilation is to provide the atmospheric boundary condition for historical simulations in the Coupled Model Intercomparison Project 6 (CMIP6) for models simulating carbon isotopes in the ocean or terrestrial biosphere. The data may also be useful for other carbon cycle modelling activities.

Engine Cycle Analysis for a Particle Bed Reactor Nuclear Rocket

DTIC Science & Technology

1991-03-01

0 DTIC USERS UNCLASSIFIED 22a. NAME OF RESPONSIBLE INDIVIDUAL ZZb. TELEPHONE (Include Area Code) 22c. OFFICE SYMBOL Lt Timothy J . Lawrence 805-275...Cycle with 2000 MW PBR and Uncooled Nozzle J : Output for Bleed Cycle with 2000 MW PBR and Cooled Nozzle K: Output for Expander Cycle with 2000 MW PBR L...Mars with carbon dioxide, the primary component of the Martian atmosphere. Carbon dioxide would delivera smaller ! j , but its use would eliminate the

Lack of anodic capacitance causes power overshoot in microbial fuel cells.

PubMed

Peng, Xinhong; Yu, Han; Yu, Hongbing; Wang, Xin

2013-06-01

Power overshoot commonly makes the performance evaluation of microbial fuel cells (MFCs) inaccurate. Here, three types of carbon with different capacitance (ultracapacitor activated carbon (UAC), plain activated carbon (PAC) and carbon black (CB)) rolled on stainless steel mesh (SSM) as anodes to investigate the relationship between overshoot and anodic capacitance. It was not observed in all cycles of UAC-MFCs (from Cycle 2 to 4) due to the largest abiotic capacitance (Cm(abiotic)) of 2.1F/cm(2), while this phenomenon was eliminated in PAC-MFCs (Cm(abiotic)=1.6 F/cm(2)) from Cycle 3 and in CB-MFCs (Cm(abiotic)=0.5F/cm(2)) from Cycle 4, indicated that the Cm(abiotic) of the anode stored charges and functioned as electron shuttle to overcome the power overshoot. With bacterial colonization, the transient charge storage in biofilm resulted in a 0.1-0.4F/cm(2) increase in total capacitance for anodes, which was the possible reason for the elimination of power overshoot in PAC/CB-MFCs after multi cycle acclimation. Copyright © 2013 Elsevier Ltd. All rights reserved.

A timeline for terrestrialization: consequences for the carbon cycle in the Palaeozoic

PubMed Central

Kenrick, Paul; Wellman, Charles H.; Schneider, Harald; Edgecombe, Gregory D.

2012-01-01

The geochemical carbon cycle is strongly influenced by life on land, principally through the effects of carbon sequestration and the weathering of calcium and magnesium silicates in surface rocks and soils. Knowing the time of origin of land plants and animals and also of key organ systems (e.g. plant vasculature, roots, wood) is crucial to understand the development of the carbon cycle and its effects on other Earth systems. Here, we compare evidence from fossils with calibrated molecular phylogenetic trees (timetrees) of living plants and arthropods. We show that different perspectives conflict in terms of the relative timing of events, the organisms involved and the pattern of diversification of various groups. Focusing on the fossil record, we highlight a number of key biases that underpin some of these conflicts, the most pervasive and far-reaching being the extent and nature of major facies changes in the rock record. These effects probably mask an earlier origin of life on land than is evident from certain classes of fossil data. If correct, this would have major implications in understanding the carbon cycle during the Early Palaeozoic. PMID:22232764

An Asymmetric Supercapacitor Based on Activated Porous Carbon Derived from Walnut Shells and NiCo₂O₄ Nanoneedle Arrays Electrodes.

PubMed

Wang, Wei; Qi, Jiqiu; Sui, Yanwei; He, Yezeng; Meng, Qingkun; Wei, Fuxiang; Jin, Yunxue

2018-08-01

A facile method was utilized to convert a common biomass of walnut shells into activated porous carbon by carbonization and activation with nitricacid treatment. The obtained activated carbon (WSs-2) exhibited excellent electrochemical performance with high specific capacitance of 137 F · g-1 at 1 A · g-1 and super cycling performance of 96% capacitance retention at 5 A · g-1 after 5000 cycles. In addition, NiCo2O4 nanoneedle arrays with good electrochemical properties were successfully prepared by a simple hydrothermal method. An aqueous asymmetric supercapacitor (ASC) device based on WSs-2 and NiCo2O4 was assembled, which delivered 21 Wh · kg-1 at a power density of 424.5 W · kg-1, and maintained 19 Wh · kg-1 at power density of 4254 W · kg-1 as well as excellent cycling stability of 99.3% capacitance retention after 5000 cycles at 4 A · g-1. Through this method, low-cost, environmentally friendly and large-scale carbon materials can be fabricated and applied in supercapacitor electrodes.

An Autonomous Mobile Platform for Underway Surface Carbon Measurements in Open-Ocean and Coastal Waters

DTIC Science & Technology

2010-06-01

Sarmiento , J ., Stephens, B. and Weller, R., 2004. Ocean Carbon and Climate Change (OCCC): An Implementation Strategy for U. S. Ocean Carbon Cycle...M. Ishii, T. Midorikawa, Y. Nojiri, A. Körtzinger, T. Steinhoff, M. Hopemma, J . Olafsson, T.S. Arnarson, B. Tilbrook, T. Johannessen, A. Olsen, R...Biogeochemical Cycles, 19, GB1009, 10.1029/2004GB002295. [5] Cai, W.- J ., Dai, M. and Wang, Y., 2006. Air-sea exchange of carbon dioxide in ocean margins: A

Amazonian forest dieback under climate-carbon cycle projections for the 21st century

NASA Astrophysics Data System (ADS)

Cox, P. M.; Betts, R. A.; Collins, M.; Harris, P. P.; Huntingford, C.; Jones, C. D.

The first GCM climate change projections to include dynamic vegetation and an interactive carbon cycle produced a very significant amplification of global warming over the 21st century. Under the IS92a ``business as usual'' emissions scenario CO2 concentrations reached about 980ppmv by 2100, which is about 280ppmv higher than when these feedbacks were ignored. The major contribution to the increased CO2 arose from reductions in soil carbon because global warming is assumed to accelerate respiration. However, there was also a lesser contribution from an alarming loss of the Amazonian rainforest. This paper describes the phenomenon of Amazonian forest dieback under elevated CO2 in the Hadley Centre climate-carbon cycle model.

Carbon-Carbon Recuperators in Closed-Brayton-Cycle Space Power Systems

NASA Technical Reports Server (NTRS)

Barrett, Michael J.; Johnson, Paul K.; Naples, Andrew G.

2006-01-01

The feasibility of using carbon-carbon (C-C) recuperators in conceptual closed-Brayton-cycle space power conversion systems was assessed. Recuperator performance expectations were forecast based on notional thermodynamic cycle state values for potential planetary missions. Resulting thermal performance, mass and volume for plate-fin C-C recuperators were estimated and quantitatively compared with values for conventional offset-strip-fin metallic designs. Mass savings of 30 to 60 percent were projected for C-C recuperators with effectiveness greater than 0.9 and thermal loads from 25 to 1400 kWt. The smaller thermal loads corresponded with lower mass savings; however, 60 percent savings were forecast for all loads above 300 kWt. System-related material challenges and compatibility issues were also discussed.

Spatial variation in below ground carbon cycling in a pristine peatland, driven by present and past vegetation

NASA Astrophysics Data System (ADS)

Mathijssen, Paul; Knorr, Klaus-Holger; Gałka, Mariusz; Borken, Werner

2017-04-01

Peat carbon cycling is controlled by both large scale factors, such as climate and hydrological setting, and small scale factors, such as microtopography, vegetation, litter quality, and rooting depth. These small scale factors commonly vary within peatlands, causing variation in the carbon balance at different locations within the same site. Understanding the relationship between small scale carbon cycling and vegetation helps us to assess the variation of carbon dynamics of peatlands, because vegetation composition acts as an integrator of factors such as microtopography, hydrology, and nutrient level. Variation in vegetation illustrates spatial variation of these underlying factors. Furthermore, the presence of certain plant species affects carbon cycling directly through litter quality or aeration through root tissues. In order to understand these within-site variations in terms of carbon cycling, we investigated carbon accumulation, decomposition, and biogeochemistry of pore waters along a transect of peat cores with changing vegetation and water levels in an ombrotrophic peatland in southern Patagonia. The transect ran from a Sphagnum magellanicum dominated spot with relatively high water table, to intermediately wet spots with mixed Sphagnum/shrubs vegetation, or dominated by Cyperaceae, eventually to a more elevated and drier spot dominated by cushion plants (mainly Astelia pumila). There were large differences in peat accumulation rates and peat densities, with faster peat growth and lower densities under Sphagnum, but overall carbon accumulation rates were quite similar in the various microenvironments. At most plots C/N ratios decreased with depth, concurrent with increasing humification index derived from FT-IR spectra. But under cushion plants this relation was opposite: more humification with depth, but also C/N ratios increases. This reflected the differing source material at depth under the cushion plants, and that the cushion plant peat layers were formed on top of Sphagnum peat. The divergent source material throughout a peat core makes it difficult to use C/N ratios to indicate peat decomposition rates. Although the low peat density and higher C/N ratios indicate that overall carbon turnover is slow at Sphagnum plots, pore water methane concentrations were elevated. At cushion plant plots, however, higher redox potentials exist until greater depths due to aerenchymous roots, inhibiting methane production and release. Our results demonstrate that large variation exists within pristine bogs, in terms of decomposition patterns, organic matter quality, and carbon turnover pathways, corresponding to variation in surface moisture levels and vegetation. Furthermore, variation in carbon cycling properties are maintained in buried peat layers and reflect more the organic material of that layer, than the current surface carbon dynamics.

A comparison between molten carbonate fuel cells based hybrid systems using air and supercritical carbon dioxide Brayton cycles with state of the art technology

NASA Astrophysics Data System (ADS)

Sánchez, D.; Muñoz de Escalona, J. M.; Chacartegui, R.; Muñoz, A.; Sánchez, T.

A proposal for high efficiency hybrid systems based on molten carbonate fuel cells is presented in this paper. This proposal is based on adopting a closed cycle bottoming gas turbine using supercritical carbon dioxide as working fluid as opposed to open cycle hot air turbines typically used in this type of power generators. First, both bottoming cycles are compared for the same operating conditions, showing that their performances do not differ as much as initially expected, even if the initial objective of reducing compression work is accomplished satisfactorily. In view of these results, a profound review of research and industrial literature is carried out in order to determine realistic specifications for the principal components of the bottoming systems. From this analysis, it is concluded that an appropriate set of specifications must be developed for each bottoming cycle as the performances of compressor, turbine and recuperator differ significantly from one working fluid to another. Thus, when the operating conditions are updated, the performances of the resulting systems show a remarkable advantage of carbon dioxide based systems over conventional air units. Actually, the proposed hybrid system shows its capability to achieve 60% net efficiency, what represents a 10% increase with respect to the reference system.

Implications of Deep Decarbonization for Carbon Cycle Science

NASA Astrophysics Data System (ADS)

Jones, A. D.; Williams, J.; Torn, M. S.

2016-12-01

The energy-system transformations required to achieve deep decarbonization in the United States, defined as a reduction of greenhouse gas emissions of 80% or more below 1990 levels by 2050, have profound implications for carbon cycle science, particularly with respect to 4 key objectives: understanding and enhancing the terrestrial carbon sink, using bioenergy sustainably, controlling non-CO2 GHGs, and emissions monitoring and verification. (1) As a source of mitigation, the terrestrial carbon sink is pivotal but uncertain, and changes in the expected sink may significantly affect the overall cost of mitigation. Yet the dynamics of the sink under changing climatic conditions, and the potential to protect and enhance the sink through land management, are poorly understood. Policy urgently requires an integrative research program that links basic science knowledge to land management practices. (2) Biomass resources can fill critical energy needs in a deeply decarbonized system, but current understanding of sustainability and lifecycle carbon aspects is limited. Mitigation policy needs better understanding of the sustainable amount, types, and cost of bioenergy feedstocks, their interactions with other land uses, and more efficient and reliable monitoring of embedded carbon. (3) As CO2 emissions from energy decrease under deep decarbonization, the relative share of non-CO2 GHGs grows larger and their mitigation more important. Because the sources tend to be distributed, variable, and uncertain, they have been under-researched. Policy needs a better understanding of mitigation priorities and costs, informed by deeper research in key areas such as fugitive CH4, fertilizer-derived N2O, and industrial F-gases. (4) The M&V challenge under deep decarbonization changes with a steep decrease in the combustion CO2 sources due to widespread electrification, while a greater share of CO2 releases is net-carbon-neutral. Similarly, gas pipelines may carry an increasing share of methane from biogenic or other net carbon-neutral sources. Improved lifecycle analysis will be needed to verify carbon neutrality, while the signal-to-noise challenge for attributing CO2 to fossil or biogenic fuels becomes more challenging.

Effects of nutrient additions on ecosystem carbon cycle in a Puerto Rican tropical wet forest

Treesearch

YIQING LI; MING XU; XIAOMING ZOU

2006-01-01

Wet tropical forests play a critical role in global ecosystem carbon (C) cycle, but C allocation and the response of different C pools to nutrient addition in these forests remain poorly understood. We measured soil organic carbon (SOC), litterfall, root biomass, microbial biomass and soil physical and chemical properties in a wet tropical forest from May 1996 to July...

40 CFR Appendix I to Subpart A of... - Global Warming Potentials (Mass Basis), Referenced to the Absolute GWP for the Adopted Carbon...

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 17 2010-07-01 2010-07-01 false Global Warming Potentials (Mass Basis), Referenced to the Absolute GWP for the Adopted Carbon Cycle Model CO2 Decay Response and Future CO2... Absolute GWP for the Adopted Carbon Cycle Model CO2 Decay Response and Future CO2 Atmospheric...

Soil Carbon and Nitrogen Cycle Modeling

NASA Astrophysics Data System (ADS)

Woo, D.; Chaoka, S.; Kumar, P.; Quijano, J. C.

2012-12-01

Second generation bioenergy crops, such as miscanthus (Miscantus × giganteus) and switchgrass (Panicum virgatum), are regarded as clean energy sources, and are an attractive option to mitigate the human-induced climate change. However, the global climate change and the expansion of perennial grass bioenergy crops have the power to alter the biogeochemical cycles in soil, especially, soil carbon storages, over long time scales. In order to develop a predictive understanding, this study develops a coupled hydrological-soil nutrient model to simulate soil carbon responses under different climate scenarios such as: (i) current weather condition, (ii) decreased precipitation by -15%, and (iii) increased temperature up to +3C for four different crops, namely miscanthus, switchgrass, maize, and natural prairie. We use Precision Agricultural Landscape Modeling System (PALMS), version 5.4.0, to capture biophysical and hydrological components coupled with a multilayer carbon and ¬nitrogen cycle model. We apply the model at daily time scale to the Energy Biosciences Institute study site, located in the University of Illinois Research Farms, in Urbana, Illinois. The atmospheric forcing used to run the model was generated stochastically from parameters obtained using available data recorded in Bondville Ameriflux Site. The model simulations are validated with observations of drainage and nitrate and ammonium concentrations recorded in drain tiles during 2011. The results of this study show (1) total soil carbon storage of miscanthus accumulates most noticeably due to the significant amount of aboveground plant carbon, and a relatively high carbon to nitrogen ratio and lignin content, which reduce the litter decomposition rate. Also, (2) the decreased precipitation contributes to the enhancement of total soil carbon storage and soil nitrogen concentration because of the reduced microbial biomass pool. However, (3) an opposite effect on the cycle is introduced by the increased temperature. The simulation results obtained in this study show differences in the soil biogeochemistry induced by the different crops analyzed. Considering the spatial scale at which this crops are cultivated this results suggest there could be important implications in the carbon and nitrogen cycle and indirect feedbacks on climate change. This study also helps us understand the future soil mineral cycle, and ensure a sustainable transition to bioenergy crops.

Influence of Large Lakes on Methane Greenhouse Forcing in the Early Eocene

NASA Astrophysics Data System (ADS)

Whiteside, J. H.; Granberg, D. L.; Kasprak, A. H.; Taylor, K. W.; Pancost, R. D.

2011-12-01

Long-duration elevated global temperatures and increased atmospheric pCO2 levels (~1000-2000 ppm) characterized the earliest portion of the Eocene (Ypressian; ~55 to 49 Ma). This extended period of global warmth was also punctuated by a series of short (sub-precessional) hyperthermal events in which atmospheric CO2 (>2000 ppm) and global temperatures rose with unprecedented and (as of yet) unexplained rapidity. This interval is perhaps the best temporal analog for assessing contemporary response of the biosphere and global carbon cycle to increased CO2 emissions. Although these hyperthermals appear paced by 100 Ka and 1 Ma scale orbital (eccentricity) cycles in the marine realm, high frequency forcing processes have not yet been examined, and long continental records have yet to be explored for their expression. To identify sub-eccentricity (<100,000 year) scale variability in Early Eocene carbon cycling, we examined lacustrine records of organic carbon isotopes and carbon content from a ~5 Ma record in the Green River Formation (GRF) in the Uinta Basin of Utah, U.S.A. and a ~1 Ma record from the Messel Shale, (Darmstadt, Germany.) We demonstrate that in addition to the expected 100 Ka eccentricity cycle, the 40 Ka cycle of obliquity is also an important component of climate variability as reflected in the lacustrine carbon cycle and hence a potential driver of global carbon cycling. We further investigated carbon cycle dynamics by examining biomarker evidence for changes in the terrestrial methane cycle during this time interval. Due to their increased volumes (>60,000 km2), highly stratified and cyclically anoxic lakes of the Eocene could have provided enough methane to alter global radiative forcing. This is consistent with our data, which demonstrate that the GRF and Messel Shale both exhibit strongly reducing conditions as well as abundant methanogen and methanotroph biomarkers. Further, the GRF lacustrine environment was highly stratified with, at times, euxinic waters extending into the photic zone, as inferred from the presence of isorenieratene derivatives. Thus, the GRF was likely an area of elevated methanogenic activity during this time. Increasing input of terrestrial matter into the GRF correlates with shifts in the pristane/phytane ratio and isorenieratane abundances, suggesting that increased runoff intensified the stratification of the lake with a transition to more anoxic conditions. Following this transition, it is likely that methane production in the GRF lake increased, which released more into the atmosphere. Our new results suggest that the global carbon cycle of the early Eocene greenhouse world was strongly mediated by both astronomical forcing (including obliquity) and increased methane production in large stratified lakes.

Effects of model structural uncertainty on carbon cycle projections: biological nitrogen fixation as a case study

NASA Astrophysics Data System (ADS)

Wieder, William R.; Cleveland, Cory C.; Lawrence, David M.; Bonan, Gordon B.

2015-04-01

Uncertainties in terrestrial carbon (C) cycle projections increase uncertainty of potential climate feedbacks. Efforts to improve model performance often include increased representation of biogeochemical processes, such as coupled carbon-nitrogen (N) cycles. In doing so, models are becoming more complex, generating structural uncertainties in model form that reflect incomplete knowledge of how to represent underlying processes. Here, we explore structural uncertainties associated with biological nitrogen fixation (BNF) and quantify their effects on C cycle projections. We find that alternative plausible structures to represent BNF result in nearly equivalent terrestrial C fluxes and pools through the twentieth century, but the strength of the terrestrial C sink varies by nearly a third (50 Pg C) by the end of the twenty-first century under a business-as-usual climate change scenario representative concentration pathway 8.5. These results indicate that actual uncertainty in future C cycle projections may be larger than previously estimated, and this uncertainty will limit C cycle projections until model structures can be evaluated and refined.

Low-surface-area hard carbon anode for Na-ion batteries via graphene oxide as a dehydration agent

DOE PAGES

Luo, Wei; Bommier, Clement; Jian, Zelang; ...

2015-02-04

Na-ion batteries are emerging as one of the most promising energy storage technologies, particularly for grid-level applications. Among anode candidate materials, hard carbon is very attractive due to its high capacity and low cost. However, hard carbon anodes often suffer a low first-cycle Coulombic efficiency and fast capacity fading. In this study, we discover that doping graphene oxide into sucrose, the precursor for hard carbon, can effectively reduce the specific surface area of hard carbon to as low as 5.4 m²/g. We further reveal that such doping can effectively prevent foaming during caramelization of sucrose and extend the pyrolysis burn-offmore » of sucrose caramel over a wider temperature range. Thus, the obtained low-surface-area hard carbon greatly improves the first-cycle Coulombic efficiency from 74% to 83% and delivers a very stable cyclic life with 95% of capacity retention after 200 cycles.« less

Wind farm and solar park effects on plant-soil carbon cycling: uncertain impacts of changes in ground-level microclimate.

PubMed

Armstrong, Alona; Waldron, Susan; Whitaker, Jeanette; Ostle, Nicholas J

2014-06-01

Global energy demand is increasing as greenhouse gas driven climate change progresses, making renewable energy sources critical to future sustainable power provision. Land-based wind and solar electricity generation technologies are rapidly expanding, yet our understanding of their operational effects on biological carbon cycling in hosting ecosystems is limited. Wind turbines and photovoltaic panels can significantly change local ground-level climate by a magnitude that could affect the fundamental plant-soil processes that govern carbon dynamics. We believe that understanding the possible effects of changes in ground-level microclimates on these phenomena is crucial to reducing uncertainty of the true renewable energy carbon cost and to maximize beneficial effects. In this Opinions article, we examine the potential for the microclimatic effects of these land-based renewable energy sources to alter plant-soil carbon cycling, hypothesize likely effects and identify critical knowledge gaps for future carbon research. © 2013 John Wiley & Sons Ltd.

Divergence in plant and microbial allocation strategies explains continental patterns in microbial allocation and biogeochemical fluxes.

PubMed

Averill, Colin

2014-10-01

Allocation trade-offs shape ecological and biogeochemical phenomena at local to global scale. Plant allocation strategies drive major changes in ecosystem carbon cycling. Microbial allocation to enzymes that decompose carbon vs. organic nutrients may similarly affect ecosystem carbon cycling. Current solutions to this allocation problem prioritise stoichiometric tradeoffs implemented in plant ecology. These solutions may not maximise microbial growth and fitness under all conditions, because organic nutrients are also a significant carbon resource for microbes. I created multiple allocation frameworks and simulated microbial growth using a microbial explicit biogeochemical model. I demonstrate that prioritising stoichiometric trade-offs does not optimise microbial allocation, while exploiting organic nutrients as carbon resources does. Analysis of continental-scale enzyme data supports the allocation patterns predicted by this framework, and modelling suggests large deviations in soil C loss based on which strategy is implemented. Therefore, understanding microbial allocation strategies will likely improve our understanding of carbon cycling and climate. © 2014 John Wiley & Sons Ltd/CNRS.

Building carbon–carbon bonds using a biocatalytic methanol condensation cycle

PubMed Central

Bogorad, Igor W.; Chen, Chang-Ting; Theisen, Matthew K.; Wu, Tung-Yun; Schlenz, Alicia R.; Lam, Albert T.; Liao, James C.

2014-01-01

Methanol is an important intermediate in the utilization of natural gas for synthesizing other feedstock chemicals. Typically, chemical approaches for building C–C bonds from methanol require high temperature and pressure. Biological conversion of methanol to longer carbon chain compounds is feasible; however, the natural biological pathways for methanol utilization involve carbon dioxide loss or ATP expenditure. Here we demonstrated a biocatalytic pathway, termed the methanol condensation cycle (MCC), by combining the nonoxidative glycolysis with the ribulose monophosphate pathway to convert methanol to higher-chain alcohols or other acetyl-CoA derivatives using enzymatic reactions in a carbon-conserved and ATP-independent system. We investigated the robustness of MCC and identified operational regions. We confirmed that the pathway forms a catalytic cycle through 13C-carbon labeling. With a cell-free system, we demonstrated the conversion of methanol to ethanol or n-butanol. The high carbon efficiency and low operating temperature are attractive for transforming natural gas-derived methanol to longer-chain liquid fuels and other chemical derivatives. PMID:25355907

Hyperdominance in Amazonian forest carbon cycling

PubMed Central

Fauset, Sophie; Johnson, Michelle O.; Gloor, Manuel; Baker, Timothy R.; Monteagudo M., Abel; Brienen, Roel J.W.; Feldpausch, Ted R.; Lopez-Gonzalez, Gabriela; Malhi, Yadvinder; ter Steege, Hans; Pitman, Nigel C.A.; Baraloto, Christopher; Engel, Julien; Pétronelli, Pascal; Andrade, Ana; Camargo, José Luís C.; Laurance, Susan G.W.; Laurance, William F.; Chave, Jerôme; Allie, Elodie; Vargas, Percy Núñez; Terborgh, John W.; Ruokolainen, Kalle; Silveira, Marcos; Aymard C., Gerardo A.; Arroyo, Luzmila; Bonal, Damien; Ramirez-Angulo, Hirma; Araujo-Murakami, Alejandro; Neill, David; Hérault, Bruno; Dourdain, Aurélie; Torres-Lezama, Armando; Marimon, Beatriz S.; Salomão, Rafael P.; Comiskey, James A.; Réjou-Méchain, Maxime; Toledo, Marisol; Licona, Juan Carlos; Alarcón, Alfredo; Prieto, Adriana; Rudas, Agustín; van der Meer, Peter J.; Killeen, Timothy J.; Marimon Junior, Ben-Hur; Poorter, Lourens; Boot, Rene G.A.; Stergios, Basil; Torre, Emilio Vilanova; Costa, Flávia R.C.; Levis, Carolina; Schietti, Juliana; Souza, Priscila; Groot, Nikée; Arets, Eric; Moscoso, Victor Chama; Castro, Wendeson; Coronado, Euridice N. Honorio; Peña-Claros, Marielos; Stahl, Clement; Barroso, Jorcely; Talbot, Joey; Vieira, Ima Célia Guimarães; van der Heijden, Geertje; Thomas, Raquel; Vos, Vincent A.; Almeida, Everton C.; Davila, Esteban Álvarez; Aragão, Luiz E.O.C.; Erwin, Terry L.; Morandi, Paulo S.; de Oliveira, Edmar Almeida; Valadão, Marco B.X.; Zagt, Roderick J.; van der Hout, Peter; Loayza, Patricia Alvarez; Pipoly, John J.; Wang, Ophelia; Alexiades, Miguel; Cerón, Carlos E.; Huamantupa-Chuquimaco, Isau; Di Fiore, Anthony; Peacock, Julie; Camacho, Nadir C. Pallqui; Umetsu, Ricardo K.; de Camargo, Plínio Barbosa; Burnham, Robyn J.; Herrera, Rafael; Quesada, Carlos A.; Stropp, Juliana; Vieira, Simone A.; Steininger, Marc; Rodríguez, Carlos Reynel; Restrepo, Zorayda; Muelbert, Adriane Esquivel; Lewis, Simon L.; Pickavance, Georgia C.; Phillips, Oliver L.

2015-01-01

While Amazonian forests are extraordinarily diverse, the abundance of trees is skewed strongly towards relatively few ‘hyperdominant' species. In addition to their diversity, Amazonian trees are a key component of the global carbon cycle, assimilating and storing more carbon than any other ecosystem on Earth. Here we ask, using a unique data set of 530 forest plots, if the functions of storing and producing woody carbon are concentrated in a small number of tree species, whether the most abundant species also dominate carbon cycling, and whether dominant species are characterized by specific functional traits. We find that dominance of forest function is even more concentrated in a few species than is dominance of tree abundance, with only ≈1% of Amazon tree species responsible for 50% of carbon storage and productivity. Although those species that contribute most to biomass and productivity are often abundant, species maximum size is also influential, while the identity and ranking of dominant species varies by function and by region. PMID:25919449

Hyperdominance in Amazonian forest carbon cycling.

PubMed

Fauset, Sophie; Johnson, Michelle O; Gloor, Manuel; Baker, Timothy R; Monteagudo M, Abel; Brienen, Roel J W; Feldpausch, Ted R; Lopez-Gonzalez, Gabriela; Malhi, Yadvinder; ter Steege, Hans; Pitman, Nigel C A; Baraloto, Christopher; Engel, Julien; Pétronelli, Pascal; Andrade, Ana; Camargo, José Luís C; Laurance, Susan G W; Laurance, William F; Chave, Jerôme; Allie, Elodie; Vargas, Percy Núñez; Terborgh, John W; Ruokolainen, Kalle; Silveira, Marcos; Aymard C, Gerardo A; Arroyo, Luzmila; Bonal, Damien; Ramirez-Angulo, Hirma; Araujo-Murakami, Alejandro; Neill, David; Hérault, Bruno; Dourdain, Aurélie; Torres-Lezama, Armando; Marimon, Beatriz S; Salomão, Rafael P; Comiskey, James A; Réjou-Méchain, Maxime; Toledo, Marisol; Licona, Juan Carlos; Alarcón, Alfredo; Prieto, Adriana; Rudas, Agustín; van der Meer, Peter J; Killeen, Timothy J; Marimon Junior, Ben-Hur; Poorter, Lourens; Boot, Rene G A; Stergios, Basil; Torre, Emilio Vilanova; Costa, Flávia R C; Levis, Carolina; Schietti, Juliana; Souza, Priscila; Groot, Nikée; Arets, Eric; Moscoso, Victor Chama; Castro, Wendeson; Coronado, Euridice N Honorio; Peña-Claros, Marielos; Stahl, Clement; Barroso, Jorcely; Talbot, Joey; Vieira, Ima Célia Guimarães; van der Heijden, Geertje; Thomas, Raquel; Vos, Vincent A; Almeida, Everton C; Davila, Esteban Álvarez; Aragão, Luiz E O C; Erwin, Terry L; Morandi, Paulo S; de Oliveira, Edmar Almeida; Valadão, Marco B X; Zagt, Roderick J; van der Hout, Peter; Loayza, Patricia Alvarez; Pipoly, John J; Wang, Ophelia; Alexiades, Miguel; Cerón, Carlos E; Huamantupa-Chuquimaco, Isau; Di Fiore, Anthony; Peacock, Julie; Camacho, Nadir C Pallqui; Umetsu, Ricardo K; de Camargo, Plínio Barbosa; Burnham, Robyn J; Herrera, Rafael; Quesada, Carlos A; Stropp, Juliana; Vieira, Simone A; Steininger, Marc; Rodríguez, Carlos Reynel; Restrepo, Zorayda; Muelbert, Adriane Esquivel; Lewis, Simon L; Pickavance, Georgia C; Phillips, Oliver L

2015-04-28

While Amazonian forests are extraordinarily diverse, the abundance of trees is skewed strongly towards relatively few 'hyperdominant' species. In addition to their diversity, Amazonian trees are a key component of the global carbon cycle, assimilating and storing more carbon than any other ecosystem on Earth. Here we ask, using a unique data set of 530 forest plots, if the functions of storing and producing woody carbon are concentrated in a small number of tree species, whether the most abundant species also dominate carbon cycling, and whether dominant species are characterized by specific functional traits. We find that dominance of forest function is even more concentrated in a few species than is dominance of tree abundance, with only ≈1% of Amazon tree species responsible for 50% of carbon storage and productivity. Although those species that contribute most to biomass and productivity are often abundant, species maximum size is also influential, while the identity and ranking of dominant species varies by function and by region.

Low-Surface-Area Hard Carbon Anode for Na-Ion Batteries via Graphene Oxide as a Dehydration Agent

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

Luo, W; Bommier, C; Jian, ZL

2015-02-04

Na-ion batteries are emerging as one of the most promising energy storage technologies, particularly for grid-level applications. Among anode candidate materials, hard carbon is very attractive due to its high capacity and low cost. However, hard carbon anodes often suffer a low first-cycle Coulombic efficiency and fast capacity fading. In this study, we discover that doping graphene oxide into sucrose, the precursor for hard carbon, can effectively reduce the specific surface area of hard carbon to as low as 5.4 m(2)/g. We further reveal that such doping can effectively prevent foaming during caramelization of sucrose and extend the pyrolysis burnoffmore » of sucrose caramel over a wider temperature range. The obtained low-surface-area hard carbon greatly improves the first-cycle Coulombic efficiency from 74% to 83% and delivers a very stable cyclic life with 95% of capacity retention after 200 cycles.« less

Impact of a Regional Drought on Terrestrial Carbon Fluxes and Atmospheric Carbon: Results from a Coupled Carbon Cycle Model

NASA Technical Reports Server (NTRS)

Lee, Eunjee; Koster, Randal D.; Ott, Lesley E.; Weir, Brad; Mahanama, Sarith; Chang, Yehui; Zeng, Fan-Wei

2017-01-01

Understanding the underlying processes that control the carbon cycle is key to predicting future global change. Much of the uncertainty in the magnitude and variability of the atmospheric carbon dioxide (CO2) stems from uncertainty in terrestrial carbon fluxes, and the relative impacts of temperature and moisture variations on regional and global scales are poorly understood. Here we investigate the impact of a regional drought on terrestrial carbon fluxes and CO2 mixing ratios over North America using the NASA Goddard Earth Observing System (GEOS) Model. Results show a sequence of changes in carbon fluxes and atmospheric CO2, induced by the drought. The relative contributions of meteorological changes to the neighboring carbon dynamics are also presented. The coupled modeling approach allows a direct quantification of the impact of the regional drought on local and proximate carbon exchange at the land surface via the carbon-water feedback processes.

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

Coker, Eric Nicholas; Miller, James E.

A thermal oxidation-reduction cycle is disclosed that uses iron titanium oxide as the reactive material. The cycle may be used for the thermal splitting of water and/or carbon dioxide to form hydrogen and/or carbon monoxide. The formed compounds may be used as syngas precursors to form fuels.

MODELING NITROGEN-CARBON CYCLING AND OXYGEN CONSUMPTION IN BOTTOM SEDIMENTS

EPA Science Inventory

A model framework is presented for simulating nitrogen and carbon cycling at the sediment–water interface, and predicting oxygen consumption by oxidation reactions inside the sediments. Based on conservation of mass and invoking simplifying assumptions, a coupled system of diffus...

CO2 diffusion into pore spaces limits weathering rate of an experimental basalt landscape

USGS Publications Warehouse

van Haren, Joost; Dontsova, Katerina; Barron-Gafford, Greg A.; Troch, Peter A.; Chorover, Jon; DeLong, Stephen B.; Breshears, David D.; Huxman, Travis E.; Pelletier, Jon D.; Saleska, Scott; Zeng, Xubin; Ruiz, Joaquin

2017-01-01

Basalt weathering is a key control over the global carbon cycle, though in situ measurements of carbon cycling are lacking. In an experimental, vegetation-free hillslope containing 330 m3 of ground basalt scoria, we measured real-time inorganic carbon dynamics within the porous media and seepage flow. The hillslope carbon flux (0.6–5.1 mg C m–2 h–1) matched weathering rates of natural basalt landscapes (0.4–8.8 mg C m–2 h–1) despite lacking the expected field-based impediments to weathering. After rainfall, a decrease in CO2 concentration ([CO2]) in pore spaces into solution suggested rapid carbon sequestration but slow reactant supply. Persistent low soil [CO2] implied that diffusion limited CO2 supply, while when sufficiently dry, reaction product concentrations limited further weathering. Strong influence of diffusion could cause spatial heterogeneity of weathering even in natural settings, implying that modeling studies need to include variable soil [CO2] to improve carbon cycling estimates associated with potential carbon sequestration methods.

Life-Cycle Assessments of Selected NASA Ground-Based Test Facilities

NASA Technical Reports Server (NTRS)

Sydnor, George Honeycutt

2012-01-01

In the past two years, two separate facility-specific life cycle assessments (LCAs) have been performed as summer student projects. The first project focused on 13 facilities managed by NASA s Aeronautics Test Program (ATP), an organization responsible for large, high-energy ground test facilities that accomplish the nation s most advanced aerospace research. A facility inventory was created for each facility, and the operational-phase carbon footprint and environmental impact were calculated. The largest impacts stemmed from electricity and natural gas used directly at the facility and to generate support processes such as compressed air and steam. However, in specialized facilities that use unique inputs like R-134a, R-14, jet fuels, or nitrogen gas, these sometimes had a considerable effect on the facility s overall environmental impact. The second LCA project was conducted on the NASA Ames Arc Jet Complex and also involved creating a facility inventory and calculating the carbon footprint and environmental impact. In addition, operational alternatives were analyzed for their effectiveness at reducing impact. Overall, the Arc Jet Complex impact is dominated by the natural-gas fired boiler producing steam on-site, but alternatives were provided that could reduce the impact of the boiler operation, some of which are already being implemented. The data and results provided by these LCA projects are beneficial to both the individual facilities and NASA as a whole; the results have already been used in a proposal to reduce carbon footprint at Ames Research Center. To help future life cycle projects, several lessons learned have been recommended as simple and effective infrastructure improvements to NASA, including better utility metering and data recording and standardization of modeling choices and methods. These studies also increased sensitivity to and appreciation for quantifying the impact of NASA s activities.

The Arctic Boreal Vulnerability Experiment: Observing, Understanding, and Predicting Social-Ecological Change in the Far North

NASA Astrophysics Data System (ADS)

Mack, M. C.; Goetz, S. J.; Kasischke, E. S.; Kimball, J. S.; Boelman, N.

2015-12-01

In the high northern latitudes, climate is warming more rapidly than anywhere else on Earth, transforming vulnerable arctic tundra and boreal forest landscapes. These changes are altering the structure and function of energy, water and carbon cycles, producing significant feedbacks to regional and global climate through changes in energy, water and carbon cycles. These changes are also challenging local and global society. At the local level, communities seek to adapt to new social-ecological regimes. At the global level, changing arctic and boreal systems are increasing becoming the focus of policy discussions at all levels of decision-making. National and international scientific efforts associated with a new NASA field campaign, the Arctic-Boreal Vulnerability Experiment (ABOVE) will advance our ability to observe, understand and predict the complex, multiscale and non-linear processes that are confronting the natural and social systems in this rapidly changing region. Over the next decade, the newly assembled ABOVE Science Team will pursue this overarching question: "How vulnerable or resilient are ecosystems and society to environmental change in the Arctic and boreal region of western North America?" Through integration of remote sensing and in situ observations with modeling of both ecological and social systems, the ABOVE Science Team will advance an interdisciplinary understanding of the Far North. In this presentation, we will discuss the conceptual basis for the ABOVE Field Campaign, describe Science Team composition and timeline, and update the community on activities. In addition, we will reflect on the visionary role of Dr. Diane Wickland, retired NASA Terrestrial Ecology Program Manager and lead of the Carbon Cycle & Ecosystems Focus Area, in the development and commencement of ABOVE.

Effect of the one‑carbon unit cycle on overall DNA methylation in children with Down's syndrome.

PubMed

Song, Cui; He, Jingyi; Chen, Jie; Liu, Youxue; Xiong, Feng; Wang, Yutian; Li, Tingyu

2015-12-01

DNA methylation is a major epigenetic mechanism regulating gene expression. In order to analyze the impact of the one‑carbon unit cycle on the overall level of DNA methylation in children with Down's syndrome (DS), the levels of indicators associated with the one‑carbon unit cycle, including folic acid (FA), vitamin B12 (VB12) and homocysteine (Hcy), and the overall DNA methylation level of DS and healthy controls (HCs) were determined in the present study. A total of 36 DS children and 40 age‑ and gender‑matched HCs were included in the present study to determine the levels of FA, VB12, Hcy and overall DNA methylation. The effect of the one‑carbon unit cycle on the overall level of DNA methylation within the DS group was analyzed. The results demonstrated that the level of VB12 was decreased (P=0.008), while the Hcy level was increased (P=0.000) in DS patients compared with the HCs. FA and VB12 levels decreased with increasing age in DS patients (P<0.05). DNA hypermethylation and hypomethylation were observed in DS patients with VB12 deficiency and hyperhomocysteinemia, respectively (P=0.031, P=0.021). Abnormalities in the one‑carbon unit cycle tend to worsen with increasing age in DS children. Thus, one‑carbon unit cycle‑associated alterations in DNA methylation may be important in the neuropathological alterations observed in DS.

Innovative Airbreathing Propulsion Concepts for Access to Space

NASA Technical Reports Server (NTRS)

Whitlow, Jr., Woodrow; Blech, Richard A.; Blankson, Isaiah M.

2001-01-01

This paper will present technologies and concepts for novel aeropropulsion systems. These technologies will enhance the safety of operations, reduce life cycle costs, and contribute to reduced costs of air travel and access to space. One of the goals of the NASA program is to reduce the carbon-dioxide emissions of aircraft engines. Engine concepts that use highly efficient fuel cell/electric drive technologies in hydrogen-fueled engines will be presented in the proposed paper. Carbon-dioxide emissions will be eliminated by replacing hydrocarbon fuel with hydrogen, and reduce NOx emissions through better combustion process control. A revolutionary exoskeletal engine concept, in which the engine drum is rotated, will be shown. This concept has the potential to allow a propulsion system that can be used for subsonic through hypersonic flight. Dual fan concepts that have ultra-high bypass ratios, low noise, and low drag will be presented. Flow-controlled turbofans and control-configured turbofans also will be discussed. To increase efficiency, a system of microengines distributed along lifting surfaces and on the fuselage is being investigated. This concept will be presented in the paper. Small propulsion systems for affordable, safe personal transportation vehicles will be discussed. These low-oil/oilless systems use technologies that enable significant cost and weight reductions. Pulse detonation engine-based hybrid-cycle and combined-cycle propulsion systems for aviation and space access will be presented.

Life support technology investment strategies for flight programs: An application of decision analysis

NASA Technical Reports Server (NTRS)

Schlater, Nelson J.; Simonds, Charles H.; Ballin, Mark G.

1993-01-01

Applied research and technology development (R&TD) is often characterized by uncertainty, risk, and significant delays before tangible returns are obtained. Given the increased awareness of limitations in resources, effective R&TD today needs a method for up-front assessment of competing technologies to help guide technology investment decisions. Such an assessment approach must account for uncertainties in system performance parameters, mission requirements and architectures, and internal and external events influencing a development program. The methodology known as decision analysis has the potential to address these issues. It was evaluated by performing a case study assessment of alternative carbon dioxide removal technologies for NASA"s proposed First Lunar Outpost program. An approach was developed that accounts for the uncertainties in each technology's cost and performance parameters as well as programmatic uncertainties such as mission architecture. Life cycle cost savings relative to a baseline, adjusted for the cost of money, was used as a figure of merit to evaluate each of the alternative carbon dioxide removal technology candidates. The methodology was found to provide a consistent decision-making strategy for the develpoment of new life support technology. The case study results provided insight that was not possible from more traditional analysis approaches.

Life support technology investment strategies for flight programs: An application of decision analysis

NASA Technical Reports Server (NTRS)

Schlater, Nelson J.; Simonds, Charles H.; Ballin, Mark G.

1993-01-01

Applied research and technology development (R&TD) is often characterized by uncertainty, risk, and significant delays before tangible returns are obtained. Given the increased awareness of limitations in resources, effective R&TD today needs a method for up-front assessment of competing technologies to help guide technology investment decisions. Such an assessment approach must account for uncertainties in system performance parameters, mission requirements and architectures, and internal and external events influencing a development program. The methodology known as decision analysis has the potential to address these issues. It was evaluated by performing a case study assessment of alternative carbon dioxide removal technologies for NASA's proposed First Lunar Outpost program. An approach was developed that accounts for the uncertainties in each technology's cost and performance parameters as well as programmatic uncertainties such as mission architecture. Life cycle cost savings relative to a baseline, adjusted for the cost of money, was used as a figure of merit to evaluate each of the alternative carbon dioxide removal technology candidates. The methodology was found to provide a consistent decision-making strategy for development of new life support technology. The case study results provided insight that was not possible from more traditional analysis approaches.

Microbial potential for carbon and nutrient cycling in a geogenic supercritical carbon dioxide reservoir: Microbial life in the deep carbonated biosphere

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

Freedman, Adam J. E.; Tan, BoonFei; Thompson, Janelle R.

Microorganisms catalyze carbon cycling and biogeochemical reactions in the deep subsurface and thus may be expected to influence the fate of injected super-critical (sc) CO 2 following geological carbon sequestration (GCS). We hypothesized that natural subsurface scCO 2 reservoirs, which serve as analogs for the long-term fate of sequestered scCO 2 harbor a ‘deep carbonated biosphere’ with carbon cycling potential. We sampled subsurface fluids from scCO 2- water separators at a natural scCO 2 reservoir at McElmo Dome, Colorado for analysis of 16S rRNA gene diversity and metagenome content. Sequence annotations indicated dominance of Sulfurospirillum, Rhizobium, Desulfovibrio and four membersmore » of the Clostridiales family. Genomes extracted from metagenomes using homology and compositional approaches revealed diverse mechanisms for growth and nutrient cycling, including pathways for CO 2 and N 2 fixation, anaerobic respiration, sulfur oxidation, fermentation and potential for metabolic syntrophy. Differences in biogeochemical potential between two production well communities were consistent with differences in fluid chemical profiles, suggesting a potential link between microbial activity and geochemistry. In conclusion, the existence of a microbial ecosystem associated with the McElmo Dome scCO 2 reservoir indicates that potential impacts of the deep biosphere on CO 2 fate and transport should be taken into consideration as a component of GCS planning and modelling.« less

Microbial potential for carbon and nutrient cycling in a geogenic supercritical carbon dioxide reservoir: Microbial life in the deep carbonated biosphere

DOE PAGES

Freedman, Adam J. E.; Tan, BoonFei; Thompson, Janelle R.

2017-05-02

Microorganisms catalyze carbon cycling and biogeochemical reactions in the deep subsurface and thus may be expected to influence the fate of injected super-critical (sc) CO 2 following geological carbon sequestration (GCS). We hypothesized that natural subsurface scCO 2 reservoirs, which serve as analogs for the long-term fate of sequestered scCO 2 harbor a ‘deep carbonated biosphere’ with carbon cycling potential. We sampled subsurface fluids from scCO 2- water separators at a natural scCO 2 reservoir at McElmo Dome, Colorado for analysis of 16S rRNA gene diversity and metagenome content. Sequence annotations indicated dominance of Sulfurospirillum, Rhizobium, Desulfovibrio and four membersmore » of the Clostridiales family. Genomes extracted from metagenomes using homology and compositional approaches revealed diverse mechanisms for growth and nutrient cycling, including pathways for CO 2 and N 2 fixation, anaerobic respiration, sulfur oxidation, fermentation and potential for metabolic syntrophy. Differences in biogeochemical potential between two production well communities were consistent with differences in fluid chemical profiles, suggesting a potential link between microbial activity and geochemistry. In conclusion, the existence of a microbial ecosystem associated with the McElmo Dome scCO 2 reservoir indicates that potential impacts of the deep biosphere on CO 2 fate and transport should be taken into consideration as a component of GCS planning and modelling.« less

Development of Advanced Eco-hydrologic and Biogeochemical Coupling Model to Constrain Missing Role of Inland Waters on Boundless Biogeochemical Cycle

NASA Astrophysics Data System (ADS)

Nakayama, T.; Maksyutov, S. S.

2016-12-01

Inland waters including rivers, lakes, and groundwater are suggested to act as a transport pathway for water and dissolved substances, and play some role in continental biogeochemical cycling (Cole et al., 2007; Battin et al., 2009). The authors have developed process-based National Integrated Catchment-based Eco-hydrology (NICE) model (Nakayama, 2014, 2015, etc.), which includes feedback between hydrologic-geomorphic-ecological processes. In this study, NICE was further developed to couple with various biogeochemical cycle models in biosphere, those for water quality in aquatic ecosystems, and those for carbon weathering, etc. (NICE-BGC) (Nakayama, accepted). The new model incorporates connectivity of the biogeochemical cycle accompanied by hydrologic cycle between surface water and groundwater, hillslopes and river networks, and other intermediate regions. The model also includes reaction between inorganic and organic carbons, and its relation to nitrogen and phosphorus in terrestrial-aquatic continuum. The model results of CO2 evasion to the atmosphere, sediment storage, and carbon transport to the ocean (DOC, POC, and DIC flux) were reasonably in good agreement with previous compiled data. The model also showed carbon budget in major river basins and in each continent in global scale. In order to decrease uncertainty about carbon cycle, it became clear the previous empirical estimation by compiled data should be extended to this process-oriented model and higher resolution data to further clarify mechanistic interplay between inorganic and organic carbon and its relationship to nitrogen and phosphorus in terrestrial-aquatic linkages. NICE-BGC would play important role to re-evaluate greenhouse gas budget of the biosphere, and to bridge gap between top-down and bottom-up approaches (Battin et al., 2009; Regnier et al., 2013).

A Novel Framework for Quantifying past Methane Recycling by Sphagnum-Methanotroph Symbiosis Using Carbon and Hydrogen Isotope Ratios of Leaf Wax Biomarkers

NASA Technical Reports Server (NTRS)

Nichols, Jonathan E.; Isles, Peter D. F.; Peteet, Dorothy M.

2014-01-01

The concentration of atmospheric methane is strongly linked to variations in Earth's climate. Currently, we can directly reconstruct the total atmospheric concentration of methane, but not individual terms of the methane cycle. Northern wetlands, dominated by Sphagnum, are an important contributor of atmospheric methane, and we seek to understand the methane cycle in these systems. We present a novel method for quantifying the proportion of carbon Sphagnum assimilates from its methanotrophic symbionts using stable isotope ratios of leaf-wax biomarkers. Carbon isotope ratios of Sphagnum compounds are determined by two competing influences, water content and the isotope ratio of source carbon. We disentangled these effects using a combined hydrogen and carbon isotope approach. We constrained Sphagnum water content using the contrast between the hydrogen isotope ratios of Sphagnum and vascular plant biomarkers. We then used Sphagnum water content to calculate the carbon isotope ratio of Sphagnum's carbon pool. Using a mass balance equation, we calculated the proportion of recycled methane contributed to the Sphagnum carbon pool, 'PRM.' We quantified PRM in peat monoliths from three microhabitats in the Mer Bleue peatland complex. Modern studies have shown that water table depth and vegetation have strong influences on the peatland methane cycle on instrumental time scales. With this new approach, delta C-13 of Sphagnum compounds are now a useful tool for investigating the relationships among hydrology, vegetation, and methanotrophy in Sphagnum peatlands over the time scales of entire peatland sediment records, vital to our understanding of the global carbon cycle through the Late Glacial and Holocene.

Evaluate the seasonal cycle and interannual variability of carbon fluxes and the associated uncertainties using modeled and observed data

NASA Astrophysics Data System (ADS)

Zeng, F.; Collatz, G. J.; Ivanoff, A.

2013-12-01

We assessed the performance of the Carnegie-Ames-Stanford Approach - Global Fire Emissions Database (CASA-GFED3) terrestrial carbon cycle model in simulating seasonal cycle and interannual variability (IAV) of global and regional carbon fluxes and uncertainties associated with model parameterization. Key model parameters were identified from sensitivity analyses and their uncertainties were propagated through model processes using the Monte Carlo approach to estimate the uncertainties in carbon fluxes and pool sizes. Three independent flux data sets, the global gross primary productivity (GPP) upscaled from eddy covariance flux measurements by Jung et al. (2011), the net ecosystem exchange (NEE) estimated by CarbonTracker, and the eddy covariance flux observations, were used to evaluate modeled fluxes and the uncertainties. Modeled fluxes agree well with both Jung's GPP and CarbonTracker NEE in the amplitude and phase of seasonal cycle, except in the case of GPP in tropical regions where Jung et al. (2011) showed larger fluxes and seasonal amplitude. Modeled GPP IAV is positively correlated (p < 0.1) with Jung's GPP IAV except in the tropics and temperate South America. The correlations between modeled NEE IAV and CarbonTracker NEE IAV are weak at regional to continental scales but stronger when fluxes are aggregated to >40°N latitude. At regional to continental scales flux uncertainties were larger than the IAV in the fluxes for both Jung's GPP and CarbonTracker NEE. Comparisons with eddy covariance flux observations are focused on sites within regions and years of recorded large-scale climate anomalies. We also evaluated modeled biomass using other independent continental biomass estimates and found good agreement. From the comparisons we identify the strengths and weaknesses of the model to capture the seasonal cycle and IAV of carbon fluxes and highlight ways to improve model performance.

Development of an advanced eco-hydrologic and biogeochemical coupling model aimed at clarifying the missing role of inland water in the global biogeochemical cycle

NASA Astrophysics Data System (ADS)

Nakayama, Tadanobu

2017-04-01

Recent research showed that inland water including rivers, lakes, and groundwater may play some role in carbon cycling, although its contribution has remained uncertain due to limited amount of reliable data available. In this study, the author developed an advanced model coupling eco-hydrology and biogeochemical cycle (National Integrated Catchment-based Eco-hydrology (NICE)-BGC). This new model incorporates complex coupling of hydrologic-carbon cycle in terrestrial-aquatic linkages and interplay between inorganic and organic carbon during the whole process of carbon cycling. The model could simulate both horizontal transports (export from land to inland water 2.01 ± 1.98 Pg C/yr and transported to ocean 1.13 ± 0.50 Pg C/yr) and vertical fluxes (degassing 0.79 ± 0.38 Pg C/yr, and sediment storage 0.20 ± 0.09 Pg C/yr) in major rivers in good agreement with previous researches, which was an improved estimate of carbon flux from previous studies. The model results also showed global net land flux simulated by NICE-BGC (-1.05 ± 0.62 Pg C/yr) decreased carbon sink a little in comparison with revised Lund-Potsdam-Jena Wetland Hydrology and Methane (-1.79 ± 0.64 Pg C/yr) and previous materials (-2.8 to -1.4 Pg C/yr). This is attributable to CO2 evasion and lateral carbon transport explicitly included in the model, and the result suggests that most previous researches have generally overestimated the accumulation of terrestrial carbon and underestimated the potential for lateral transport. The results further implied difference between inverse techniques and budget estimates suggested can be explained to some extent by a net source from inland water. NICE-BGC would play an important role in reevaluation of greenhouse gas budget of the biosphere, quantification of hot spots, and bridging the gap between top-down and bottom-up approaches to global carbon budget.

iTREE: Long-term variability of tree growth in a changing environment - identifying physiological mechanisms using stable C and O isotopes in tree rings.

NASA Astrophysics Data System (ADS)

Siegwolf, R. T. W.; Buchmann, N.; Frank, D.; Joos, F.; Kahmen, A.; Treydte, K.; Leuenberger, M.; Saurer, M.

2012-04-01

Trees play are a critical role in the carbon cycle - their photosynthetic assimilation is one of the largest terrestrial carbon fluxes and their standing biomass represents the largest carbon pool of the terrestrial biosphere. Understanding how tree physiology and growth respond to long-term environmental change is pivotal to predict the magnitude and direction of the terrestrial carbon sink. iTREE is an interdisciplinary research framework to capitalize on synergies among leading dendroclimatologists, plant physiologists, isotope specialists, and global carbon cycle modelers with the objectives of reducing uncertainties related to tree/forest growth in the context of changing natural environments. Cross-cutting themes in our project are tree rings, stable isotopes, and mechanistic modelling. We will (i) establish a European network of tree-ring based isotope time-series to retrodict interannual to long-term tree physiological changes, (ii) conduct laboratory and field experiments to adapt a mechanistic isotope model to derive plant physiological variables from tree-ring isotopes, (iii) implement this model into a dynamic global vegetation model, and perform subsequent model-data validation exercises to refine model representation of plant physiological processes and (iv) attribute long-term variation in tree growth to plant physiological and environmental drivers, and identify how our refined knowledge revises predictions of the coupled carbon-cycle climate system. We will contribute to i) advanced quantifications of long-term variation in tree growth across Central Europe, ii) novel long-term information on key physiological processes that underlie variations in tree growth, and iii) improved carbon cycle models that can be employed to revise predictions of the coupled carbon-cycle climate system. Hence iTREE will significantly contribute towards a seamless understanding of the responses of terrestrial ecosystems to long-term environmental change, and ultimately help reduce uncertainties of the magnitude and direction of the past and future terrestrial carbon sink.

The impact of agricultural soil erosion on the global carbon cycle

USGS Publications Warehouse

Van Oost, Kristof; Quine, T.A.; Govers, G.; De Gryze, S.; Six, J.; Harden, J.W.; Ritchie, J.C.; McCarty, G.W.; Heckrath, G.; Kosmas, C.; Giraldez, J.V.; Marques Da Silva, J.R.; Merckx, R.

2007-01-01

Agricultural soil erosion is thought to perturb the global carbon cycle, but estimates of its effect range from a source of 1 petagram per year -1 to a sink of the same magnitude. By using caesium-137 and carbon inventory measurements from a large-scale survey, we found consistent evidence for an erosion-induced sink of atmospheric carbon equivalent to approximately 26% of the carbon transported by erosion. Based on this relationship, we estimated a global carbon sink of 0.12 (range 0.06 to 0.27) petagrams of carbon per year-1 resulting from erosion in the world's agricultural landscapes. Our analysis directly challenges the view that agricultural erosion represents an important source or sink for atmospheric CO2.

Ten years of multiple data stream assimilation with the ORCHIDEE land surface model to improve regional to global simulated carbon budgets: synthesis and perspectives on directions for the future

NASA Astrophysics Data System (ADS)

Peylin, P. P.; Bacour, C.; MacBean, N.; Maignan, F.; Bastrikov, V.; Chevallier, F.

2017-12-01

Predicting the fate of carbon stocks and their sensitivity to climate change and land use/management strongly relies on our ability to accurately model net and gross carbon fluxes. However, simulated carbon and water fluxes remain subject to large uncertainties, partly because of unknown or poorly calibrated parameters. Over the past ten years, the carbon cycle data assimilation system at the Laboratoire des Sciences du Climat et de l'Environnement has investigated the benefit of assimilating multiple carbon cycle data streams into the ORCHIDEE LSM, the land surface component of the Institut Pierre Simon Laplace Earth System Model. These datasets have included FLUXNET eddy covariance data (net CO2 flux and latent heat flux) to constrain hourly to seasonal time-scale carbon cycle processes, remote sensing of the vegetation activity (MODIS NDVI) to constrain the leaf phenology, biomass data to constrain "slow" (yearly to decadal) processes of carbon allocation, and atmospheric CO2 concentrations to provide overall large scale constraints on the land carbon sink. Furthermore, we have investigated technical issues related to multiple data stream assimilation and choice of optimization algorithm. This has provided a wide-ranging perspective on the challenges we face in constraining model parameters and thus better quantifying, and reducing, model uncertainty in projections of the future global carbon sink. We review our past studies in terms of the impact of the optimization on key characteristics of the carbon cycle, e.g. the partition of the northern latitudes vs tropical land carbon sink, and compare to the classic atmospheric flux inversion approach. Throughout, we discuss our work in context of the abovementioned challenges, and propose solutions for the community going forward, including the potential of new observations such as atmospheric COS concentrations and satellite-derived Solar Induced Fluorescence to constrain the gross carbon fluxes of the ORCHIDEE model.

Subalpine Forest Carbon Cycling Short- and Long-Term Influence ofClimate and Species

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

Kueppers, L.; Harte, J.

2005-08-23

Ecosystem carbon cycle feedbacks to climate change comprise one of the largest remaining sources of uncertainty in global model predictions of future climate. Both direct climate effects on carbon cycling and indirect effects via climate-induced shifts in species composition may alter ecosystem carbon balance over the long term. In the short term, climate effects on carbon cycling may be mediated by ecosystem species composition. We used an elevational climate and tree species composition gradient in Rocky Mountain subalpine forest to quantify the sensitivity of all major ecosystem carbon stocks and fluxes to these factors. The climate sensitivities of carbon fluxesmore » were species-specific in the cases of relative above ground productivity and litter decomposition, whereas the climate sensitivity of dead wood decay did not differ between species, and total annual soil CO2 flux showed no strong climate trend. Lodge pole pine relative productivity increased with warmer temperatures and earlier snowmelt, while Engelmann spruce relative productivity was insensitive to climate variables. Engelmann spruce needle decomposition decreased linearly with increasing temperature(decreasing litter moisture), while lodgepole pine and subalpine fir needle decay showed a hump-shaped temperature response. We also found that total ecosystem carbon declined by 50 percent with a 2.88C increase in mean annual temperature and a concurrent 63 percent decrease ingrowing season soil moisture, primarily due to large declines in mineral soil and dead wood carbon. We detected no independent effect of species composition on ecosystem C stocks. Overall, our carbon flux results suggest that, in the short term, any change in subalpine forest net carbon balance will depend on the specific climate scenario and spatial distribution of tree species. Over the long term, our carbon stock results suggest that with regional warming and drying, Rocky Mountain subalpine forest will be a net source of carbon to the atmosphere.« less

Developing a dynamic life cycle greenhouse gas emission inventory for wood construction for two different end-of-life scenarios

Treesearch

Richard D. Bergman; James Salazar; Scott Bowe

2012-01-01

Static life cycle assessment does not fully describe the carbon footprint of construction wood because of carbon changes in the forest and product pools over time. This study developed a dynamic greenhouse gas (GHG) inventory approach using US Forest Service and life-cycle data to estimate GHG emissions on construction wood for two different end-of-life scenarios....

Scenarios for Low Carbon and Low Water Electric Power Plant Operations: Implications for Upstream Water Use.

PubMed

Dodder, Rebecca S; Barnwell, Jessica T; Yelverton, William H

2016-11-01

Electric sector water use, in particular for thermoelectric operations, is a critical component of the water-energy nexus. On a life cycle basis per unit of electricity generated, operational (e.g., cooling system) water use is substantially higher than water demands for the fuel cycle (e.g., natural gas and coal) and power plant manufacturing (e.g., equipment and construction). However, could shifting toward low carbon and low water electric power operations create trade-offs across the electricity life cycle? We compare business-as-usual with scenarios of carbon reductions and water constraints using the MARKet ALlocation (MARKAL) energy system model. Our scenarios show that, for water withdrawals, the trade-offs are minimal: operational water use accounts for over 95% of life cycle withdrawals. For water consumption, however, this analysis identifies potential trade-offs under some scenarios. Nationally, water use for the fuel cycle and power plant manufacturing can reach up to 26% of the total life cycle consumption. In the western United States, nonoperational consumption can even exceed operational demands. In particular, water use for biomass feedstock irrigation and manufacturing/construction of solar power facilities could increase with high deployment. As the United States moves toward lower carbon electric power operations, consideration of shifting water demands can help avoid unintended consequences.

Evidence for a spike in mantle carbon outgassing during the Ediacaran period

NASA Astrophysics Data System (ADS)

Paulsen, Timothy; Deering, Chad; Sliwinski, Jakub; Bachmann, Olivier; Guillong, Marcel

2017-12-01

Long-term cycles in Earth's climate are thought to be primarily controlled by changes in atmospheric CO2 concentrations. Changes in carbon emissions from volcanic activity can create an imbalance in the carbon cycle. Large-scale changes in volcanic activity have been inferred from proxies such as the age abundance of detrital zircons, but the magnitude of carbon emissions depends on the style of volcanism as well as the amount. Here we analyse U-Pb age and trace element data of detrital zircons from Antarctica and compare the results with the global rock record. We identify a spike in CO2-rich carbonatite and alkaline magmatism during the Ediacaran period. Before the Ediacaran, secular cooling of the mantle and the advent of cooler subduction regimes promoted the sequestration of carbon derived from decarbonation of subducting oceanic slabs in the mantle. We infer that subsequent magmatism led to the extensive release of carbon that may at least in part be recorded in the Shuram-Wonoka carbon isotope excursion. We therefore suggest that this pulse of alkaline volcanism reflects a profound reorganization of the Neoproterozoic deep and surface carbon cycles and promoted planetary warming before the Cambrian radiation.

High sulfur-containing carbon polysulfide polymer as a novel cathode material for lithium-sulfur battery.

PubMed

Zhang, Yiyong; Peng, Yueying; Wang, Yunhui; Li, Jiyang; Li, He; Zeng, Jing; Wang, Jing; Hwang, Bing Joe; Zhao, Jinbao

2017-09-12

The lithium-sulfur battery, which offers a high energy density and is environmental friendly, is a promising next generation of rechargeable energy storage system. However, despite these attractive attributes, the commercialization of lithium-sulfur battery is primarily hindered by the parasitic reactions between the Li metal anode and dissolved polysulfide species from the cathode during the cycling process. Herein, we synthesize the sulfur-rich carbon polysulfide polymer and demonstrate that it is a promising cathode material for high performance lithium-sulfur battery. The electrochemical studies reveal that the carbon polysulfide polymer exhibits superb reversibility and cycle stability. This is due to that the well-designed structure of the carbon polysulfide polymer has several advantages, especially, the strong chemical interaction between sulfur and the carbon framework (C-S bonds) inhibits the shuttle effect and the π electrons of the carbon polysulfide compound enhance the transfer of electrons and Li + . Furthermore, as-prepared carbon polysulfide polymer-graphene hybrid cathode achieves outstanding cycle stability and relatively high capacity. This work highlights the potential promise of the carbon polysulfide polymer as the cathode material for high performance lithium-sulfur battery.

Recent increases in terrestrial carbon uptake at little cost to the water cycle.

PubMed

Cheng, Lei; Zhang, Lu; Wang, Ying-Ping; Canadell, Josep G; Chiew, Francis H S; Beringer, Jason; Li, Longhui; Miralles, Diego G; Piao, Shilong; Zhang, Yongqiang

2017-07-24

Quantifying the responses of the coupled carbon and water cycles to current global warming and rising atmospheric CO 2 concentration is crucial for predicting and adapting to climate changes. Here we show that terrestrial carbon uptake (i.e. gross primary production) increased significantly from 1982 to 2011 using a combination of ground-based and remotely sensed land and atmospheric observations. Importantly, we find that the terrestrial carbon uptake increase is not accompanied by a proportional increase in water use (i.e. evapotranspiration) but is largely (about 90%) driven by increased carbon uptake per unit of water use, i.e. water use efficiency. The increased water use efficiency is positively related to rising CO 2 concentration and increased canopy leaf area index, and negatively influenced by increased vapour pressure deficits. Our findings suggest that rising atmospheric CO 2 concentration has caused a shift in terrestrial water economics of carbon uptake.The response of the coupled carbon and water cycles to anthropogenic climate change is unclear. Here, the authors show that terrestrial carbon uptake increased significantly from 1982 to 2011 and that this increase is largely driven by increased water-use efficiency, rather than an increase in water use.