A Fe-C-Ca big cycle in modern carbon-intensive industries: toward emission reduction and resource utilization

PubMed Central

Sun, Yongqi; Sridhar, Seetharaman; Seetharaman, Seshadri; Wang, Hao; Liu, Lili; Wang, Xidong; Zhang, Zuotai

2016-01-01

Herein a big Fe-C-Ca cycle, clarifying the basic element flows and energy flows in modern carbon-intensive industries including the metallurgical industry and the cement industry, was proposed for the first time in the contexts of emission reduction and iron ore degradation nowadays. This big cycle was focused on three industrial elements of Fe, C and Ca and thus it mainly comprised three interdependent loops, i.e., a C-cycle, a Fe-cycle and a Ca-path. As exemplified, we started from the integrated disposal of hot steel slags, a man-made iron resource via char gasification and the employment of hematite, a natural iron resource greatly extended the application area of this idea. Accordingly, based on this concept, the theoretical potentials for energy saving, emission reduction and Fe resource recovery achieved in modern industry are estimated up to 7.66 Mt of standard coal, 63.9 Mt of CO2 and 25.2 Mt of pig iron, respectively. PMID:26923104

A Fe-C-Ca big cycle in modern carbon-intensive industries: toward emission reduction and resource utilization

NASA Astrophysics Data System (ADS)

Sun, Yongqi; Sridhar, Seetharaman; Seetharaman, Seshadri; Wang, Hao; Liu, Lili; Wang, Xidong; Zhang, Zuotai

2016-02-01

Herein a big Fe-C-Ca cycle, clarifying the basic element flows and energy flows in modern carbon-intensive industries including the metallurgical industry and the cement industry, was proposed for the first time in the contexts of emission reduction and iron ore degradation nowadays. This big cycle was focused on three industrial elements of Fe, C and Ca and thus it mainly comprised three interdependent loops, i.e., a C-cycle, a Fe-cycle and a Ca-path. As exemplified, we started from the integrated disposal of hot steel slags, a man-made iron resource via char gasification and the employment of hematite, a natural iron resource greatly extended the application area of this idea. Accordingly, based on this concept, the theoretical potentials for energy saving, emission reduction and Fe resource recovery achieved in modern industry are estimated up to 7.66 Mt of standard coal, 63.9 Mt of CO2 and 25.2 Mt of pig iron, respectively.

Revealing lithium-silicide phase transformations in nano-structured silicon-based lithium ion batteries via in situ NMR spectroscopy.

PubMed

Ogata, K; Salager, E; Kerr, C J; Fraser, A E; Ducati, C; Morris, A J; Hofmann, S; Grey, C P

2014-01-01

Nano-structured silicon anodes are attractive alternatives to graphitic carbons in rechargeable Li-ion batteries, owing to their extremely high capacities. Despite their advantages, numerous issues remain to be addressed, the most basic being to understand the complex kinetics and thermodynamics that control the reactions and structural rearrangements. Elucidating this necessitates real-time in situ metrologies, which are highly challenging, if the whole electrode structure is studied at an atomistic level for multiple cycles under realistic cycling conditions. Here we report that Si nanowires grown on a conducting carbon-fibre support provide a robust model battery system that can be studied by (7)Li in situ NMR spectroscopy. The method allows the (de)alloying reactions of the amorphous silicides to be followed in the 2nd cycle and beyond. In combination with density-functional theory calculations, the results provide insight into the amorphous and amorphous-to-crystalline lithium-silicide transformations, particularly those at low voltages, which are highly relevant to practical cycling strategies.

Carbon Cycle Science in Support of Decision-Making

NASA Astrophysics Data System (ADS)

Brown, M. E.; West, T. O.; McGlynn, E.; Gurwick, N. P.; Duren, R. M.; Ocko, I.; Paustian, K.

2016-12-01

There has been an extensive amount of basic and applied research conducted on biogeochemical cycles, land cover change, watershed to earth system modeling, climate change, and energy efficiency. Concurrently, there continues to be interest in how to best reduce net carbon emissions, including maintaining or augmenting global carbon stocks and decreasing fossil fuel emissions. Decisions surrounding reductions in net emissions should be grounded in, and informed by, existing scientific knowledge and analyses in order to be most effective. The translation of scientific research to decision-making is rarely direct, and often requires coordination of objectives or intermediate research steps. For example, complex model output may need to be simplified to provide mean estimates for given activities; biogeochemical models used for climate change prediction may need to be altered to estimate net carbon flux associated with particular activities; or scientific analyses may need to aggregate and analyze data in a different manner to address specific questions. In the aforementioned cases, expertise and capabilities of researchers and decision-makers are both needed, and early coordination and communication is most effective. Initial analysis of existing science and current decision-making needs indicate that (a) knowledge that is co-produced by scientists and decision-makers has a higher probability of being usable for decision making, (b) scientific work in the past decade to integrate activity data into models has resulted in more usable information for decision makers, (c) attribution and accounting of carbon cycle fluxes is key to using carbon cycle science for decision-making, and (d) stronger, long-term links among research on climate and management of carbon-related sectors (e.g., energy, land use, industry, and buildings) are needed to adequately address current issues.

Understanding the Science of Environmental Issues: Development of a Subject Knowledge Guide for Primary Teacher Education.

ERIC Educational Resources Information Center

Summers, Mike; Kruger, Colin; Childs, Ann; Mant, Jenny

2001-01-01

Uses a questionnaire to explore understanding in practicing primary school teachers (n=170), primary trainees (n= 120), and secondary science trainees (n=88) in the areas of biodiversity, carbon cycle, ozone, and global warming. Suggests that both basic explanations and difficulties in understanding of teachers in some areas can usefully inform…

Rethinking the global carbon cycle with a large, dynamic and microbially mediated gas hydrate capacitor

NASA Astrophysics Data System (ADS)

Dickens, Gerald R.

2003-08-01

Prominent negative δ13C excursions characterize several past intervals of abrupt (<100 kyr) environmental change. These anomalies, best exemplified by the >2.5‰ drop across the Paleocene/Eocene thermal maximum (PETM) ca. 55.5 Ma, command our attention because they lack explanation with conventional models for global carbon cycling. Increasingly, Earth scientists have argued that they signify massive release of CH4 from marine gas hydrates, although typically without considering the underlying process or the ensuing ramifications of such an interpretation. At the most basic level, a large, dynamic 'gas hydrate capacitor' stores and releases 13C-depleted carbon at rates linked to external conditions such as deep ocean temperature. The capacitor contains three internal reservoirs: dissolved gas, gas hydrate, and free gas. Carbon enters and leaves these reservoirs through microbial decomposition of organic matter, anaerobic oxidation of CH4 in shallow sediment, and seafloor gas venting; carbon cycles between these reservoirs through several processes, including fluid flow, precipitation and dissolution of gas hydrate, and burial. Numerical simulations show that simple gas hydrate capacitors driven by inferred changes in bottom water warming during the PETM can generate a global δ13C excursion that mimics observations. The same modeling extended over longer time demonstrates that variable CH4 fluxes to and from gas hydrates can partly explain other δ13C excursions, rapid and slow, large and small, negative and positive. Although such modeling is rudimentary (because processes and variables in modern and ancient gas hydrate systems remain poorly constrained), acceptance of a vast, externally regulated gas hydrate capacitor forces us to rethink δ13C records and the operation of the global carbon cycle throughout time.

Biologically mediated isotope fractionations - Biochemistry, geochemical significance and preservation in the earth's oldest sediments

NASA Technical Reports Server (NTRS)

Schidlowski, M.

1983-01-01

Preferential metabolization of isotopically light carbon and sulfur has resulted in a fractionation of the stable isotopes of these elements on a global scale, with the light species (C-12, S-32) markedly concentrated in biogenic materials. Since the biological effects are basically retained when carbon and sulfur are incorporated in sediments, the respective fractionations are propagated into the rock section of the geochemical cycle, this having consequently caused a characteristic bipartition of both elements between 'light' and 'heavy' crustal reservoirs. Preservation of the biological isotope effects in sedimentary rocks makes it possible to trace the underlying biochemical processes back over most of the geological record. According to the available evidence, biological (autotrophic) carbon fixation arose prior to 3.5(if not 3.8) billion years ago, while the emergence of dissimilatory sulfate reduction antedates the appearance of the oldest presumably bacteriogenic sulfur isotope patterns in rocks between 2.7 and 2.8 billion years old. Hence, biological control of the terrestrial carbon and sulfur cycles has been established very early in the earth's history.

Predictors of Drought Recovery across Forest Ecosystems

NASA Astrophysics Data System (ADS)

Anderegg, W.

2016-12-01

The impacts of climate extremes on terrestrial ecosystems are poorly understood but central 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 basic plant physiological understanding. Here, we discuss what we have learned about forest ecosystem recovery from extreme drought across spatial and temporal scales, drawing on inference from tree rings, eddy covariance data, large scale gross primary productivity products, and ecosystem models. In tree rings, we find pervasive and substantial "legacy effects" of reduced growth and incomplete recovery for 1-4 years after severe drought, and that legacy effects are most prevalent in dry ecosystems, Pinaceae, and species with low hydraulic safety margins. At larger scales, we see relatively rapid recovery of ecosystem fluxes, with strong influences of ecosystem productivity and diversity and longer recovery periods in high latidue forests. In contrast, no or limited legacy effects are simulated in current climate-vegetation models after drought, and we highlight some of the key missing mechanisms in dynamic vegetation models. Our results reveal hysteresis in forest ecosystem carbon cycling and delayed recovery from climate extremes and help advance a predictive understanding of ecosystem recovery.

SEEPLUS: A SIMPLE ONLINE CLIMATE MODEL

NASA Astrophysics Data System (ADS)

Tsutsui, Junichi

A web application for a simple climate model - SEEPLUS (a Simple climate model to Examine Emission Pathways Leading to Updated Scenarios) - has been developed. SEEPLUS consists of carbon-cycle and climate-change modules, through which it provides the information infrastructure required to perform climate-change experiments, even on a millennial-timescale. The main objective of this application is to share the latest scientific knowledge acquired from climate modeling studies among the different stakeholders involved in climate-change issues. Both the carbon-cycle and climate-change modules employ impulse response functions (IRFs) for their key processes, thereby enabling the model to integrate the outcome from an ensemble of complex climate models. The current IRF parameters and forcing manipulation are basically consistent with, or within an uncertainty range of, the understanding of certain key aspects such as the equivalent climate sensitivity and ocean CO2 uptake data documented in representative literature. The carbon-cycle module enables inverse calculation to determine the emission pathway required in order to attain a given concentration pathway, thereby providing a flexible way to compare the module with more advanced modeling studies. The module also enables analytical evaluation of its equilibrium states, thereby facilitating the long-term planning of global warming mitigation.

Fabrication of Carbon-Platinum Interdigitated Array Electrodes and Their Application for Investigating Homogeneous Hydrogen Evolution Catalysis

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

Liu, Fei; Divan, Ralu; Parkinson, Bruce A.

2015-06-29

Carbon interdigitated array (IDA) electrodes have been applied to study the homogeneous hydrogen evolution electrocatalyst [Ni(PPh2NBn2)2]2+ (where PPh2NBn2 is 1,5-dibenzyl-3,7-diphenyl-1,5-diaza-3,7-diphosphacyclooctane). The existence of reaction intermediates in the catalytic cycle is inferred from the electrochemical behavior of a glassy carbon disk electrodes and carbon IDA electrodes. The currents on IDA electrodes for an EC’ (electron transfer reaction followed by a catalytic reaction) mechanism are derived from the number of redox cycles and the contribution of non-catalytic currents. The catalytic reaction rate constant was then extracted from the IDA current equations. Applying the IDA current and kinetic equations to the electrochemical responsemore » of the [Ni(PPh2NBn2)2]2+ catalyst yielded a rate constant of 0.10 s-1 for the hydrogen evolution reaction that agrees with the literature value. The quantitative analysis of IDA cyclic voltammetry can be used as a simple and straightforward method for determining rate constants in other catalytic systems. This work was supported as part of the Center for Molecular Electrocatalysis, an Energy Frontier Research Center funded by the Department of Energy, Office of Science, Office of Basic Energy Sciences. Pacific Northwest National Laboratory is operated by Battelle for DOE. Use of the Center for Nanoscale Materials was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.« less

The Ocean Carbon States Database: A Proof-of-Concept Application of Cluster Analysis in the Ocean Carbon Cycle

NASA Technical Reports Server (NTRS)

Latto, Rebecca; Romanou, Anastasia

2018-01-01

In this paper, we present a database of the basic regimes of the carbon cycle in the ocean, the 'ocean carbon states', as obtained using a data mining/pattern recognition technique in observation-based as well as model data. The goal of this study is to establish a new data analysis methodology, test it and assess its utility in providing more insights into the regional and temporal variability of the marine carbon cycle. This is important as advanced data mining techniques are becoming widely used in climate and Earth sciences and in particular in studies of the global carbon cycle, where the interaction of physical and biogeochemical drivers confounds our ability to accurately describe, understand, and predict CO2 concentrations and their changes in the major planetary carbon reservoirs. In this proof-of-concept study, we focus on using well-understood data that are based on observations, as well as model results from the NASA Goddard Institute for Space Studies (GISS) climate model. Our analysis shows that ocean carbon states are associated with the subtropical-subpolar gyre during the colder months of the year and the tropics during the warmer season in the North Atlantic basin. Conversely, in the Southern Ocean, the ocean carbon states can be associated with the subtropical and Antarctic convergence zones in the warmer season and the coastal Antarctic divergence zone in the colder season. With respect to model evaluation, we find that the GISS model reproduces the cold and warm season regimes more skillfully in the North Atlantic than in the Southern Ocean and matches the observed seasonality better than the spatial distribution of the regimes. Finally, the ocean carbon states provide useful information in the model error attribution. Model air-sea CO2 flux biases in the North Atlantic stem from wind speed and salinity biases in the subpolar region and nutrient and wind speed biases in the subtropics and tropics. Nutrient biases are shown to be most important in the Southern Ocean flux bias.

Chemistry Cube Game - Exploring Basic Principles of Chemistry by Turning Cubes.

PubMed

Müller, Markus T

2018-02-01

The Chemistry Cube Game invites students at secondary school level 1 and 2 to explore basic concepts of chemistry in a playful way, either as individuals or in teams. It consists of 15 different cubes, 9 cubes for different acids, their corresponding bases and precursors, and 6 cubes for different reducing and oxidising agents. The cubes can be rotated in those directions indicated. Each 'allowed' vertical or horizontal rotation of 90° stands for a chemical reaction or a physical transition. Two different games and playing modes are presented here: First, redox chemistry is introduced for the formation of salts from elementary metals and non-metals. Second, the speciation of acids and bases at different pH-values is shown. The cubes can be also used for games about environmental chemistry such as the carbon and sulphur cycle, covering the topic of acid rain, or the nitrogen cycle including ammoniac synthesis, nitrification and de-nitrification.

Final Technical Report for Award # ER64999

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

Metcalf, William W.

2014-10-08

This report provides a summary of activities for Award # ER64999, a Genomes to Life Project funded by the Office of Science, Basic Energy Research. The project was entitled "Methanogenic archaea and the global carbon cycle: a systems biology approach to the study of Methanosarcina species". The long-term goal of this multi-investigator project was the creation of integrated, multiscale models that accurately and quantitatively predict the role of Methanosarcina species in the global carbon cycle under dynamic environmental conditions. To achieve these goals we pursed four specific aims: (1) genome sequencing of numerous members of the Order Methanosarcinales, (2) identificationmore » of genomic sources of phenotypic variation through in silico comparative genomics, (3) elucidation of the transcriptional networks of two Methanosarcina species, and (4) development of comprehensive metabolic network models for characterized strains to address the question of how metabolic models scale with genetic distance.« less

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.

Potassium Secondary Batteries.

PubMed

Eftekhari, Ali; Jian, Zelang; Ji, Xiulei

2017-02-08

Potassium may exhibit advantages over lithium or sodium as a charge carrier in rechargeable batteries. Analogues of Prussian blue can provide millions of cyclic voltammetric cycles in aqueous electrolyte. Potassium intercalation chemistry has recently been demonstrated compatible with both graphite and nongraphitic carbons. In addition to potassium-ion batteries, potassium-O 2 (or -air) and potassium-sulfur batteries are emerging. Additionally, aqueous potassium-ion batteries also exhibit high reversibility and long cycling life. Because of potentially low cost, availability of basic materials, and intriguing electrochemical behaviors, this new class of secondary batteries is attracting much attention. This mini-review summarizes the current status, opportunities, and future challenges of potassium secondary batteries.

The Ocean Carbon States Database: a proof-of-concept application of cluster analysis in the ocean carbon cycle

NASA Astrophysics Data System (ADS)

Latto, Rebecca; Romanou, Anastasia

2018-03-01

In this paper, we present a database of the basic regimes of the carbon cycle in the ocean, the ocean carbon states, as obtained using a data mining/pattern recognition technique in observation-based as well as model data. The goal of this study is to establish a new data analysis methodology, test it and assess its utility in providing more insights into the regional and temporal variability of the marine carbon cycle. This is important as advanced data mining techniques are becoming widely used in climate and Earth sciences and in particular in studies of the global carbon cycle, where the interaction of physical and biogeochemical drivers confounds our ability to accurately describe, understand, and predict CO2 concentrations and their changes in the major planetary carbon reservoirs. In this proof-of-concept study, we focus on using well-understood data that are based on observations, as well as model results from the NASA Goddard Institute for Space Studies (GISS) climate model. Our analysis shows that ocean carbon states are associated with the subtropical-subpolar gyre during the colder months of the year and the tropics during the warmer season in the North Atlantic basin. Conversely, in the Southern Ocean, the ocean carbon states can be associated with the subtropical and Antarctic convergence zones in the warmer season and the coastal Antarctic divergence zone in the colder season. With respect to model evaluation, we find that the GISS model reproduces the cold and warm season regimes more skillfully in the North Atlantic than in the Southern Ocean and matches the observed seasonality better than the spatial distribution of the regimes. Finally, the ocean carbon states provide useful information in the model error attribution. Model air-sea CO2 flux biases in the North Atlantic stem from wind speed and salinity biases in the subpolar region and nutrient and wind speed biases in the subtropics and tropics. Nutrient biases are shown to be most important in the Southern Ocean flux bias. All data and analysis scripts are available at https://data.giss.nasa.gov/oceans/carbonstates/ (DOI: https://doi.org/10.5281/zenodo.996891).

The Tropospheric Lifetimes of Halocarbons and Their Reactions with OH Radicals: an Assessment Based on the Concentration of CO-14

NASA Technical Reports Server (NTRS)

Derwent, Richard G.; Volz-Thomas, Andreas

1990-01-01

Chemical reaction with hydroxyl radicals formed in the troposphere from ozone photolysis in the presence of methane, carbon monoxide and nitrogen oxides provides an important removal mechanism for halocarbons containing C-H and C = C double bonds. The isotropic distribution in atmospheric carbon monoxide was used to quantify the tropospheric hydroxyl radical distribution. Here, this methodology is reevaluated in the light of recent chemical kinetic data evaluations and new understandings gained in the life cycles of methane and carbon monoxide. None of these changes has forced a significant revision in the CO-14 approach. However, it is somewhat more clearly apparent how important basic chemical kinetic data are to the accurate establishment of the tropospheric hydroxyl radical distribution.

Fluxes of carbon dioxide and methane from diverse aquatic environments in an agricultural landscape

NASA Astrophysics Data System (ADS)

Stanley, E. H.; Crawford, J. T.; Loken, L. C.; Casson, N. J.; Gubbins, N. J.; Oliver, S. K.

2014-12-01

The contribution of aquatic environments to landscape carbon cycling is particularly apparent in carbon- and water-rich regions. Such areas arguably represent an end member in terms of the relative significance of aquatic carbon cycling, while dry, carbon-poor zones are the likely opposing end member. Not surprisingly, most limnological attention has focused on these former regions, leaving open questions as to how aquatic systems in other locales influence larger-scale carbon dynamics. This includes human-dominated landscapes where agricultural and urban land uses can fundamentally alter carbon dynamics. Surveys of streams, ponds, and lakes in a southern Wisconsin landscape highlight three findings relevant to understanding the role of these aquatic systems in larger-scale carbon dynamics. First, streams and ponds had unexpectedly high summertime concentrations in and fluxes of CO2 and CH4. These values were approximately an order of magnitude greater than for less disturbed, forest and wetland-dominated landscapes in northern Wisconsin. Second, while mean C gas concentrations in lakes were lower than in streams and ponds, detailed spatial measurements demonstrate variability in surface water CO2 (43-1090 ppm pCO2) and CH4 (6-839 ppm pCH4) within a lake on a single day is similar to that observed among 25 streams included in our survey (260-6000 ppm pCO2; 50-600 ppm pCH4). This small-scale heterogeneity highlights a basic challenge for upscaling site-specific data collected at one or a few points to the whole lake and across lakes. Third, while agricultural and urban ecosystems are not necessarily carbon-rich environments, area-specific carbon storage in streams and ponds is substantial (up to 3000-5000 g C per m2). Further, carbon storage was strongly related to CH4 concentrations in streams, as C-rich sediments provided both an environment and substrate to fuel methanogenesis. The picture that emerges of C processing in aquatic environments throughout this human-dominated landscape is one of large C pools and fluxes and high spatial variability, suggesting that these land uses may be accelerating rates of aquatic C cycling and amplifying the role of these ecosystems in anthropogenic landscapes.

Cyclostratigraphy across a Mississippian carbonate ramp in the Esfahan-Sirjan Basin, Iran: implications for the amplitudes and frequencies of sea-level fluctuations along the southern margin of the Paleotethys

NASA Astrophysics Data System (ADS)

Bayet-Goll, Aram; Esfahani, Fariba Shirezadeh; Daraei, Mehdi; Monaco, Paolo; Sharafi, Mahmoud; Mohammadi, Amir Akbari

2018-03-01

The Tournaisian-Visean carbonate successions of the Esfahan-Sirjan Basin (ESB) from Sanandaj-Sirjan Zone, Iran, have been used to generate a sequence stratigraphic model that enhances facies characterization and improves paleoenvironmental interpretation of shallow marine successions deposited along the southern margin of the Paleotethys. Detailed facies analysis allowed to differentiate seven facies, which, in order of decreasing abundance, are: (1) shaly and marly, F1; (2) peloidal mudstones/wackestones, F2; (3) peloidal/bioclastic packstones, F3; (4) intraclastic/bioclastic packstones/grainstones, F4; (5) oolitic/bioclastic packstone/grainstone, F5; (6) sandy intraclastic/bioclastic grainstones, F6; (7) sandy oolitic/bioclastic grainstones, F7. The different facies can be grouped into three facies associations that correspond to different environments of a carbonate platform with ramp geometry (homoclinal), from outer ramp (F1 and F2), mid-ramp (F3, F4 and F6) to inner ramp areas (F5 and F7). Meter-scale cycles are the basic building blocks of shallow marine carbonate successions of the Tournaisian-Viséan ramp of the ESB. Small-scale cycles are stacked into medium-scale cycles that in turn are building blocks of large-scale cycles. According to the recognized facies and the stacking pattern of high-frequency cycles across the ramp, five large-scale cycles in the southeastern outcrops (Tournaisian-Viséan) and three large-scale cycles in the northwest outcrops (Viséan) related to eustatic sea-level changes can be recognized. The overall retrogradational nature of the carbonate ramp, illustrated by both vertical facies relationships and the stacking patterns of high-frequency cycles within the third-order cycles, implies that the deposition of the Tournaisian-Viséan successions mainly took place under a long-term transgressive sea-level trend. The stratigraphic architectural style of the sequences, characterized by the lack of lowstand deposits and exposure surfaces, associated with the evidence of progressive increase in the proportion of backstepping of facies belts across bounding surfaces and predominant subtidal characteristics, is in accordance with the long-term transgressive sea-level trend and greenhouse conditions during the Tournaisian-Viséan. The continued transgression on this broad shelfal platform could lead to the shutdown of the shallow water carbonate factory, reduction in sediment supply or sediment transport towards the offshore setting and the development of give-up sequences. The association of transgressive events with the deposition of thick open-marine marls/shales is a common feature in Tournaisian to Viséan times of the southern margin of the Paleotethys.

An Integrated Use of Experimental, Modeling and Remote Sensing Techniques to Investigate Carbon and Phosphorus Dynamics in the Humid Tropics

NASA Technical Reports Server (NTRS)

Townsend, Alan R.; Asner, Gregory P.; Bustamante, Mercedes M. C.

2001-01-01

Moist tropical forests comprise one of the world's largest and most diverse biomes, and exchange more carbon, water, and energy with the atmosphere than any other ecosystem. In recent decades, tropical forests have also become one of the globe's most threatened biomes, subjected to exceptionally high rates of deforestation and land degradation. Thus, the importance of and threats to tropical forests are undeniable, yet our understanding of basic ecosystem processes in both intact and disturbed portions of the moist tropics remains poorer than for almost any other major biome. Our approach in this project was to take a multi-scale, multi-tool approach to address two different problems. First, we wanted to test if land-use driven changes in the cycles of probable limiting nutrients in forest systems were a key driver in the frequently observed pattern of declining pasture productivity and carbon stocks. Given the enormous complexity of land use change in the tropics, in which one finds a myriad of different land use types and intensities overlain on varying climates and soil types, we also wanted to see if new remote sensing techniques would allow some novel links between parameters which could be sensed remotely, and key biogeochemical variables which cannot. Second, we addressed to general questions about the role of tropical forests in the global carbon cycle. First, we used a new approach for quantifying and minimizing non-biological artifacts in the NOAA/NASA AVHRR Pathfinder time series of surface reflectance data so that we could address potential links between Amazonian forest dynamics and ENSO cycles. Second, we showed that the disequilibrium in C-13 exchanged between land and atmosphere following tropical deforestation probably has a significant impact on the use of 13-CO2 data to predict regional fluxes in the global carbon cycle.

Energy Security: From Deal Killers to Game Changers

NASA Astrophysics Data System (ADS)

Cooke, Charlie

2010-03-01

Five energy security ``deal killers" are identified: 1) Global warming and CO2 emissions from fossil fuel combustion; 2) Intermittent energy sources (wind, solar) and the presence and stability of the grid; 3) Penetration of plant defenses to produce transportation fuels from biomass; 4) Mimicking nature: artificial photosynthesis for solar energy to fuels; and 5) Spent fuel from nuclear power reactors. Transformational basic research is required to successfully change the ground rules, to transform these ``deal killers" into ``game changers." T hey are: 1) Offsetting carbon capture and storage costs through enhanced oil recovery and methane generation from high temperature geothermal saline aquifers; 2) Electrical energy storage, through batteries and super-capacitors; 3) Genetic modification of plant cell walls, and catalytic methods for transforming plant sugars into fuels; 4) Separation of solar-induced electrons from holes, and catalysis to produce fuels; and 5) Closing the nuclear fuel cycle. Basic research can revolutionize our approach to carbon-free energy by enhancing nature to achieve energy security.

Tropical rainforests dominate multi-decadal variability of the global carbon cycle

NASA Astrophysics Data System (ADS)

Zhang, X.; Wang, Y. P.; Peng, S.; Rayner, P. J.; Silver, J.; Ciais, P.; Piao, S.; Zhu, Z.; Lu, X.; Zheng, X.

2017-12-01

Recent studies find that inter-annual variability of global atmosphere-to-land CO2 uptake (NBP) is dominated by semi-arid ecosystems. However, the NBP variations at decadal to multi-decadal timescales are still not known. By developing a basic theory for the role of net primary production (NPP) and heterotrophic respiration (Rh) on NBP and applying it to 100-year simulations of terrestrial ecosystem models forced by observational climate, we find that tropical rainforests dominate the multi-decadal variability of global NBP (48%) rather than the semi-arid lands (35%). The NBP variation at inter-annual timescales is almost 90% contributed by NPP, but across longer timescales is progressively controlled by Rh that constitutes the response from the NPP-derived soil carbon input (40%) and the response of soil carbon turnover rates to climate variability (60%). The NBP variations of tropical rainforests is modulated by the ENSO and the PDO through their significant influences on temperature and precipitation at timescales of 2.5-7 and 25-50 years, respectively. This study highlights the importance of tropical rainforests on the multi-decadal variability of global carbon cycle, suggesting that we need to carefully differentiate the effect of NBP long-term fluctuations associated with ocean-related climate modes on the long-term trend in land sink.

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.

A Nanopore-Structured Nitrogen-Doped Biocarbon Electrocatalyst for Oxygen Reduction from Two-Step Carbonization of Lemna minor Biomass

NASA Astrophysics Data System (ADS)

Guo, Chaozhong; Li, Zhongbin; Niu, Lidan; Liao, Wenli; Sun, Lingtao; Wen, Bixia; Nie, Yunqing; Cheng, Jing; Chen, Changguo

2016-05-01

So far, the development of highly active and stable carbon-based electrocatalysts for oxygen reduction reaction (ORR) to replace commercial Pt/C catalyst is a hot topic. In this study, a new nanoporous nitrogen-doped carbon material was facilely designed by two-step pyrolysis of the renewable Lemna minor enriched in crude protein under a nitrogen atmosphere. Electrochemical measurements show that the onset potential for ORR on this carbon material is around 0.93 V (versus reversible hydrogen electrode), slightly lower than that on the Pt/C catalyst, but its cycling stability is higher compared to the Pt/C catalyst in an alkaline medium. Besides, the ORR at this catalyst approaches to a four-electron transfer pathway. The obtained ORR performance can be basically attributed to the formation of high contents of pyridinic and graphitic nitrogen atoms inside this catalyst. Thus, this work opens up the path in the ORR catalysis for the design of nitrogen-doped carbon materials utilizing aquatic plants as starting precursors.

Ultrahigh volumetric capacitance and cyclic stability of fluorine and nitrogen co-doped carbon microspheres

NASA Astrophysics Data System (ADS)

Zhou, Junshuang; Lian, Jie; Hou, Li; Zhang, Junchuan; Gou, Huiyang; Xia, Meirong; Zhao, Yufeng; Strobel, Timothy A.; Tao, Lu; Gao, Faming

2015-09-01

Highly porous nanostructures with large surface areas are typically employed for electrical double-layer capacitors to improve gravimetric energy storage capacity; however, high surface area carbon-based electrodes result in poor volumetric capacitance because of the low packing density of porous materials. Here, we demonstrate ultrahigh volumetric capacitance of 521 F cm-3 in aqueous electrolytes for non-porous carbon microsphere electrodes co-doped with fluorine and nitrogen synthesized by low-temperature solvothermal route, rivaling expensive RuO2 or MnO2 pseudo-capacitors. The new electrodes also exhibit excellent cyclic stability without capacitance loss after 10,000 cycles in both acidic and basic electrolytes at a high charge current of 5 A g-1. This work provides a new approach for designing high-performance electrodes with exceptional volumetric capacitance with high mass loadings and charge rates for long-lived electrochemical energy storage systems.

Variational methods to estimate terrestrial ecosystem model parameters

NASA Astrophysics Data System (ADS)

Delahaies, Sylvain; Roulstone, Ian

2016-04-01

Carbon is at the basis of the chemistry of life. Its ubiquity in the Earth system is the result of complex recycling processes. Present in the atmosphere in the form of carbon dioxide it is adsorbed by marine and terrestrial ecosystems and stored within living biomass and decaying organic matter. Then soil chemistry and a non negligible amount of time transform the dead matter into fossil fuels. Throughout this cycle, carbon dioxide is released in the atmosphere through respiration and combustion of fossils fuels. Model-data fusion techniques allow us to combine our understanding of these complex processes with an ever-growing amount of observational data to help improving models and predictions. The data assimilation linked ecosystem carbon (DALEC) model is a simple box model simulating the carbon budget allocation for terrestrial ecosystems. Over the last decade several studies have demonstrated the relative merit of various inverse modelling strategies (MCMC, ENKF, 4DVAR) to estimate model parameters and initial carbon stocks for DALEC and to quantify the uncertainty in the predictions. Despite its simplicity, DALEC represents the basic processes at the heart of more sophisticated models of the carbon cycle. Using adjoint based methods we study inverse problems for DALEC with various data streams (8 days MODIS LAI, monthly MODIS LAI, NEE). The framework of constraint optimization allows us to incorporate ecological common sense into the variational framework. We use resolution matrices to study the nature of the inverse problems and to obtain data importance and information content for the different type of data. We study how varying the time step affect the solutions, and we show how "spin up" naturally improves the conditioning of the inverse problems.

A U.S. Carbon Cycle Science Plan

NASA Astrophysics Data System (ADS)

Michalak, Anna M.; Jackson, Rob; Marland, Gregg; Sabine, Christopher

2009-03-01

First Meeting of the Carbon Cycle Science Working Group; Washington, D. C., 17-18 November 2008; The report “A U.S. carbon cycle science plan” (J. L. Sarmiento and S. C. Wofsy, U.S. Global Change Res. Program, Washington, D. C., 1999) outlined research priorities and promoted coordinated carbon cycle research across federal agencies for nearly a decade. Building on this framework and subsequent reports (available at http://www.carboncyclescience.gov/docs.php), the Carbon Cycle Science Working Group (CCSWG) was formed in 2008 to develop an updated strategy for the next decade. The recommendations of the CCSWG will go to agency managers who have collective responsibility for setting national carbon cycle science priorities and for sponsoring much of the carbon cycle research in the United States.

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

Liese, Eric; Zitney, Stephen E.

A multi-stage centrifugal compressor model is presented with emphasis on analyzing use of an exit flow coefficient vs. an inlet flow coefficient performance parameter to predict off-design conditions in the critical region of a supercritical carbon dioxide (CO 2) power cycle. A description of the performance parameters is given along with their implementation in a design model (number of stages, basic sizing, etc.) and a dynamic model (for use in transient studies). A design case is shown for two compressors, a bypass compressor and a main compressor, as defined in a process simulation of a 10 megawatt (MW) supercritical COmore » 2 recompression Brayton cycle. Simulation results are presented for a simple open cycle and closed cycle process with changes to the inlet temperature of the main compressor which operates near the CO 2 critical point. Results showed some difference in results using the exit vs. inlet flow coefficient correction, however, it was not significant for the range of conditions examined. Here, this paper also serves as a reference for future works, including a full process simulation of the 10 MW recompression Brayton cycle.« less

A Nanopore-Structured Nitrogen-Doped Biocarbon Electrocatalyst for Oxygen Reduction from Two-Step Carbonization of Lemna minor Biomass.

PubMed

Guo, Chaozhong; Li, Zhongbin; Niu, Lidan; Liao, Wenli; Sun, Lingtao; Wen, Bixia; Nie, Yunqing; Cheng, Jing; Chen, Changguo

2016-12-01

So far, the development of highly active and stable carbon-based electrocatalysts for oxygen reduction reaction (ORR) to replace commercial Pt/C catalyst is a hot topic. In this study, a new nanoporous nitrogen-doped carbon material was facilely designed by two-step pyrolysis of the renewable Lemna minor enriched in crude protein under a nitrogen atmosphere. Electrochemical measurements show that the onset potential for ORR on this carbon material is around 0.93 V (versus reversible hydrogen electrode), slightly lower than that on the Pt/C catalyst, but its cycling stability is higher compared to the Pt/C catalyst in an alkaline medium. Besides, the ORR at this catalyst approaches to a four-electron transfer pathway. The obtained ORR performance can be basically attributed to the formation of high contents of pyridinic and graphitic nitrogen atoms inside this catalyst. Thus, this work opens up the path in the ORR catalysis for the design of nitrogen-doped carbon materials utilizing aquatic plants as starting precursors.

The GLOBE Carbon Project: Integrating the Science of Carbon Cycling and Climate Change into K-12 Classrooms.

NASA Astrophysics Data System (ADS)

Ollinger, S. V.; Silverberg, S.; Albrechtova, J.; Freuder, R.; Gengarelly, L.; Martin, M.; Randolph, G.; Schloss, A.

2007-12-01

The global carbon cycle is a key regulator of the Earth's climate and is central to the normal function of ecological systems. Because rising atmospheric CO2 is the principal cause of climate change, understanding how ecosystems cycle and store carbon has become an extremely important issue. In recent years, the growing importance of the carbon cycle has brought it to the forefront of both science and environmental policy. The need for better scientific understanding has led to establishment of numerous research programs, such as the North American Carbon Program (NACP), which seeks to understand controls on carbon cycling under present and future conditions. Parallel efforts are greatly needed to integrate state-of-the-art science on the carbon cycle and its importance to climate with education and outreach efforts that help prepare society to make sound decisions on energy use, carbon management and climate change adaptation. Here, we present a new effort that joins carbon cycle scientists with the International GLOBE Education program to develop carbon cycle activities for K-12 classrooms. The GLOBE Carbon Cycle project is focused on bringing cutting edge research and research techniques in the field of terrestrial ecosystem carbon cycling into the classroom. Students will collect data about their school field site through existing protocols of phenology, land cover and soils as well as new protocols focused on leaf traits, and ecosystem growth and change. They will also participate in classroom activities to understand carbon cycling in terrestrial ecosystems, these will include plant- a-plant experiments, hands-on demonstrations of various concepts, and analysis of collected data. In addition to the traditional GLOBE experience, students will have the opportunity to integrate their data with emerging and expanding technologies including global and local carbon cycle models and remote sensing toolkits. This program design will allow students to explore research questions from local to global scales with both present and future environmental conditions.

Diurnal patterns of productivity of arbuscular mycorrhizal fungi revealed with the Soil Ecosystem Observatory.

PubMed

Hernandez, Rebecca R; Allen, Michael F

2013-10-01

Arbuscular mycorrhizal (AM) fungi are the most abundant plant symbiont and a major pathway of carbon sequestration in soils. However, their basic biology, including their activity throughout a 24-h day : night cycle, remains unknown. We employed the in situ Soil Ecosystem Observatory to quantify the rates of diurnal growth, dieback and net productivity of extra-radical AM fungi. AM fungal hyphae showed significantly different rates of growth and dieback over a period of 24 h and paralleled the circadian-driven photosynthetic oscillations observed in plants. The greatest rates (and incidences) of growth and dieback occurred between noon and 18:00 h. Growth and dieback events often occurred simultaneously and were tightly coupled with soil temperature and moisture, suggesting a rapid acclimation of the external phase of AM fungi to the immediate environment. Changes in the environmental conditions and variability of the mycorrhizosphere may alter the diurnal patterns of productivity of AM fungi, thereby modifying soil carbon sequestration, nutrient cycling and host plant success. © 2013 The Authors. New Phytologist © 2013 New Phytologist Trust.

Diurnal patterns of productivity of arbuscular mycorrhizal fungi revealed with the Soil Ecosystem Observatory

PubMed Central

Hernandez, Rebecca R; Allen, Michael F

2013-01-01

Arbuscular mycorrhizal (AM) fungi are the most abundant plant symbiont and a major pathway of carbon sequestration in soils. However, their basic biology, including their activity throughout a 24-h day : night cycle, remains unknown. We employed the in situ Soil Ecosystem Observatory to quantify the rates of diurnal growth, dieback and net productivity of extra-radical AM fungi. AM fungal hyphae showed significantly different rates of growth and dieback over a period of 24 h and paralleled the circadian-driven photosynthetic oscillations observed in plants. The greatest rates (and incidences) of growth and dieback occurred between noon and 18:00 h. Growth and dieback events often occurred simultaneously and were tightly coupled with soil temperature and moisture, suggesting a rapid acclimation of the external phase of AM fungi to the immediate environment. Changes in the environmental conditions and variability of the mycorrhizosphere may alter the diurnal patterns of productivity of AM fungi, thereby modifying soil carbon sequestration, nutrient cycling and host plant success. PMID:23844990

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.

Assessing and Synthesizing the Last Decade of Research on the Major Pools and Fluxes of the Carbon Cycle in the US and North America: An Interagency Governmental Perspective

NASA Astrophysics Data System (ADS)

Cavallaro, N.; Shrestha, G.; Stover, D. B.; Zhu, Z.; Ombres, E. H.; Deangelo, B.

2015-12-01

The 2nd State of the Carbon Cycle Report (SOCCR-2) is focused on US and North American carbon stocks and fluxes in managed and unmanaged systems, including relevant carbon management science perspectives and tools for supporting and informing decisions. SOCCR-2 is inspired by the US Carbon Cycle Science Plan (2011) which emphasizes global scale research on long-lived, carbon-based greenhouse gases, carbon dioxide and methane, and the major pools and fluxes of the global carbon cycle. Accordingly, the questions framing the Plan inform this report's topical roadmap, with a focus on US and North America in the global context: 1) How have natural processes and human actions affected the global carbon cycle on land, in the atmosphere, in the oceans and in the ecosystem interfaces (e.g. coastal, wetlands, urban-rural)? 2) How have socio-economic trends affected the levels of the primary carbon-containing gases, carbon dioxide and methane, in the atmosphere? 3) How have species, ecosystems, natural resources and human systems been impacted by increasing greenhouse gas concentrations, the associated changes in climate, and by carbon management decisions and practices? To address these aspects, SOCCR-2 will encompass the following broad assessment framework: 1) Carbon Cycle at Scales (Global Perspective, North American Perspective, US Perspective, Regional Perspective); 2) Role of carbon in systems (Soils; Water, Oceans, Vegetation; Terrestrial-aquatic Interfaces); 3) Interactions/Disturbance/Impacts from/on the carbon cycle. 4) Carbon Management Science Perspective and Decision Support (measurements, observations and monitoring for research and policy relevant decision-support etc.). In this presentation, the Carbon Cycle Interagency Working Group and the U.S. Global Change Research Program's U.S. Carbon Cycle Science Program Office will highlight the scientific context, strategy, structure, team and production process of the report, which is part of the USGCRP's Sustained National Climate Assessment process.

A New U.S. Carbon Cycle Science Plan

NASA Astrophysics Data System (ADS)

Michalak, A. M.; Jackson, R.; Marland, G.; Sabine, C.

2009-05-01

The report "A U.S. carbon cycle science plan" (J. L. Sarmiento and S. C. Wofsy, U.S. Global Change Res. Program, Washington, D. C., 1999) outlined research priorities and promoted coordinated carbon cycle research across federal agencies in the United States for nearly a decade. Building on this framework and subsequent reports (http://www.carboncyclescience.gov/docs.php), a working group comprised of 27 scientists was formed in 2008 under the United States Carbon Cycle Science Program to review the 1999 Science Plan, and to develop an updated strategy for carbon cycle research for the period from 2010 to 2020. This comprehensive review is being conducted with wide input from the research and stakeholder communities. The recommendations of the Carbon Cycle Science Working Group (CCSWG) will go to U.S. agency managers who have collective responsibility for setting national carbon cycle science priorities and for sponsoring much of the carbon cycle research in the United States. This presentation will provide an update on the ongoing planning process, will outline the steps that the CCSWG is undertaking in building consensus towards an updated U.S. Carbon Cycle Science Plan, and will seek input on the best ways in which to coordinate efforts with ongoing and upcoming research in Canada and Mexico, as well as with ongoing work globally.

Electrochemical performance and interfacial investigation on Si composite anode for lithium ion batteries in full cell

NASA Astrophysics Data System (ADS)

Shobukawa, Hitoshi; Alvarado, Judith; Yang, Yangyuchen; Meng, Ying Shirley

2017-08-01

Lithium ion batteries (LIBs) containing silicon (Si) as a negative electrode have gained much attention recently because they deliver high energy density. However, the commercialization of LIBs with Si anode is limited due to the unstable electrochemical performance associated with expansion and contraction during electrochemical cycling. This study investigates the electrochemical performance and degradation mechanism of a full cell containing Si composite anode and LiFePO4 (lithium iron phosphate (LFP)) cathode. Enhanced electrochemical cycling performance is observed when the full cell is cycled with fluoroethylene carbonate (FEC) additive compared to the standard electrolyte. To understand the improvement in the electrochemical performance, x-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and scanning electron microscopy (SEM) are used. Based on the electrochemical behavior, FEC improves the reversibility of lithium ion diffusion into the solid electrolyte interphase (SEI) on the Si composite anode. Moreover, XPS analysis demonstrates that the SEI composition generated from the addition of FEC consists of a large amount of LiF and less carbonate species, which leads to better capacity retention over 40 cycles. The effective SEI successively yields more stable capacity retention and enhances the reversibility of lithium ion diffusion through the interphase of the Si anode, even at higher discharge rate. This study contributes to a basic comprehension of electrochemical performance and SEI formation of LIB full cells with a high loading Si composite anode.

Molecular and Imaging Insights into the Formation of Soil Organic Matter in a Red Pine Rhizosphere

NASA Astrophysics Data System (ADS)

Dohnalkova, A.; Tfaily, M.; Smith, A. P.; Chu, R. K.; Crump, A.; Brislawn, C.; Varga, T.; Shi, Z.; Thomashow, L. S.; Harsh, J. B.; Balogh-Brunstad, Z.; Keller, C. K.

2017-12-01

Microbially-derived carbon inputs to soils play an important role in forming soil organic matter (SOM), but detailed knowledge of basic mechanisms of carbon (C) cycling, such as stabilization of organic C compounds originating from rhizodeposition, is limited. The objective of this study aimed to investigate the stability of rhizosphere-produced carbon components in a model laboratory mesocosm of Pinus resinosa grown in a designed mineral soil mix. We hypothesized that nutrient limitation would cause formation of microbially-produced C constituents that would contribute to SOM stabilization. We focused on the processes of rhizodeposition in the rhizosphere, and we utilized a suite of advanced imaging and molecular techniques to obtain a molecular-level identification of the microbial community and the newly-formed SOM compounds in the rhizosphere and the bulk soil. We considered implications regarding their degree of long-term stability. The microbes in this controlled, nutrient-limited system, without pre-existing organic matter, produced extracellular polymeric substances that formed associations with nutrient-bearing minerals and contributed to the microbial mineral weathering process. Electron microscopy revealed unique ultrastructural residual signatures of biogenic C compounds, and the increased presence of an amorphous organic phase associated with the mineral phase was evidenced by X-ray diffraction. These findings provide insight into the various degrees of stability of microbial SOM products in ecosystems and evidence that the residual biogenic material associated with mineral matrices may be important components in current carbon cycle models.

Institutional Context of Carbon Cycle Science Research in the U.S. and North America - A SOCCR perspective

NASA Astrophysics Data System (ADS)

Shrestha, G.; Cavallaro, N.; Ste-Marie, C.

2016-12-01

Carbon cycle science has been a research priority in the U.S. for decades. Interagency coordination interests and research needs in U.S. carbon cycle science led to the establishment of the U.S. Carbon Cycle Science Program, the North American Carbon Program (NACP), the Ocean Carbon and Biogeochemistry Program (OCB) and other intergovernmental collaboration platforms such as CarboNA, involving the U.S., Mexico and Canada. This presentation highlights some of these activities, and the historical context, the institutional frameworks and the operational mechanisms that have helped to facilitate and advance large scale collaborative research in carbon cycle in the U.S. and North America.

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/

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.

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.

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

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.

The Impeller Exit Flow Coefficient As a Performance Map Variable for Predicting Centrifugal Compressor Off-Design Operation Applied to a Supercritical CO 2 Working Fluid

DOE PAGES

Liese, Eric; Zitney, Stephen E.

2017-06-26

A multi-stage centrifugal compressor model is presented with emphasis on analyzing use of an exit flow coefficient vs. an inlet flow coefficient performance parameter to predict off-design conditions in the critical region of a supercritical carbon dioxide (CO 2) power cycle. A description of the performance parameters is given along with their implementation in a design model (number of stages, basic sizing, etc.) and a dynamic model (for use in transient studies). A design case is shown for two compressors, a bypass compressor and a main compressor, as defined in a process simulation of a 10 megawatt (MW) supercritical COmore » 2 recompression Brayton cycle. Simulation results are presented for a simple open cycle and closed cycle process with changes to the inlet temperature of the main compressor which operates near the CO 2 critical point. Results showed some difference in results using the exit vs. inlet flow coefficient correction, however, it was not significant for the range of conditions examined. Here, this paper also serves as a reference for future works, including a full process simulation of the 10 MW recompression Brayton cycle.« less

The Impeller Exit Flow Coefficient As a Performance Map Variable for Predicting Centrifugal Compressor Off-Design Operation Applied to a Supercritical CO 2 Working Fluid

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

Liese, Eric; Zitney, Stephen E.

A multi-stage centrifugal compressor model is presented with emphasis on analyzing use of an exit flow coefficient vs. an inlet flow coefficient performance parameter to predict off-design conditions in the critical region of a supercritical carbon dioxide (CO 2) power cycle. A description of the performance parameters is given along with their implementation in a design model (number of stages, basic sizing, etc.) and a dynamic model (for use in transient studies). A design case is shown for two compressors, a bypass compressor and a main compressor, as defined in a process simulation of a 10 megawatt (MW) supercritical COmore » 2 recompression Brayton cycle. Simulation results are presented for a simple open cycle and closed cycle process with changes to the inlet temperature of the main compressor which operates near the CO 2 critical point. Results showed some difference in results using the exit vs. inlet flow coefficient correction, however, it was not significant for the range of conditions examined. Here, this paper also serves as a reference for future works, including a full process simulation of the 10 MW recompression Brayton cycle.« less

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…

The Importance of Uncertainty and Sensitivity Analysis in Process-based Models of Carbon and Nitrogen Cycling in Terrestrial Ecosystems with Particular Emphasis on Forest Ecosystems — Selected Papers from a Workshop Organized by the International Society for Ecological Modelling (ISEM) at the Third Biennal Meeting of the International Environmental Modelling and Software Society (IEMSS) in Burlington, Vermont, USA, August 9-13, 2006

USGS Publications Warehouse

Larocque, Guy R.; Bhatti, Jagtar S.; Liu, Jinxun; Ascough, James C.; Gordon, Andrew M.

2008-01-01

Many process-based models of carbon (C) and nitrogen (N) cycles have been developed for terrestrial ecosystems, including forest ecosystems. They address many basic issues of ecosystems structure and functioning, such as the role of internal feedback in ecosystem dynamics. The critical factor in these phenomena is scale, as these processes operate at scales from the minute (e.g. particulate pollution impacts on trees and other organisms) to the global (e.g. climate change). Research efforts remain important to improve the capability of such models to better represent the dynamics of terrestrial ecosystems, including the C, nutrient, (e.g. N) and water cycles. Existing models are sufficiently well advanced to help decision makers develop sustainable management policies and planning of terrestrial ecosystems, as they make realistic predictions when used appropriately. However, decision makers must be aware of their limitations by having the opportunity to evaluate the uncertainty associated with process-based models (Smith and Heath, 2001 and Allen et al., 2004). The variation in scale of issues currently being addressed by modelling efforts makes the evaluation of uncertainty a daunting task.

Improved blackwater disinfection using potentiodynamic methods with oxidized boron-doped diamond electrodes.

PubMed

Thostenson, J O; Mourouvin, R; Hawkins, B T; Ngaboyamahina, E; Sellgren, K L; Parker, C B; Deshusses, M A; Stoner, B R; Glass, J T

2018-09-01

Electrochemical disinfection (ECD) has become an important blackwater disinfection technology. ECD is a promising solution for the 2 billion people without access to conventional sanitation practices and in areas deficient in basic utilities (e.g., sewers, electricity, waste treatment). Here, we report on the disinfection of blackwater using potential cycling compared to potentiostatic treatment methods in chloride-containing and chloride-free solutions of blackwater (i.e., untreated wastewater containing feces, urine, and flushwater from a toilet). Potentiodynamic treatment is demonstrated to improve disinfection energy efficiency of blackwater by 24% and 124% compared to static oxidation and reduction methods, respectively. The result is shown to be caused by electrochemical advanced oxidation processes (EAOP) and regeneration of sp 2 -surface-bonded carbon functional groups that serve the dual purpose of catalysts and adsorption sites of oxidant intermediates. Following 24 h electrolysis in blackwater, electrode fouling is shown to be minimized by the potential cycling method when compared to equivalent potentiostatic methods. The potential cycling current density is 40% higher than both the static oxidative and reductive methods. This work enhances the understanding of oxygen reduction catalysts using functionalized carbon materials and electrochemical disinfection anodes, both of which have the potential to bring a cost-effective, energy efficient, and practical solution to the problem of disinfecting blackwater. Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.

An ecohydraulic view on stream resilience and ecosystem functioning - what can science teach management?

NASA Astrophysics Data System (ADS)

Battin, Tom J.; Dzubakova, Katharina; Boodoo, Kyle; Ulseth, Amber

2017-04-01

Streams and rivers are increasingly exposed to environmental change across various spatial and temporal scales. Consequently, ecosystem health and integrity are becoming compromised. Most management strategies designed to recover and maintain stream ecosystem health involve engineering measures of geomorphology. The success of such engineering measures relies on a thorough understanding of the underlying physical, chemical and biological process coupling across scales. First, we present results from experimental work unraveling the relevance of streambed heterogeneity for the resilience of phototrophic biofilms. This is critical as phototrophic biofilms are key for nutrient removal and hence for keeping the water clean. These biofilms are also the machinery of primary production and related carbon fluxes in stream ecosystems. Next, we show how climate change may affect primary production, including CO2, in streams and the networks they form. In fact, streams are now recognized as major sources of CO2 to the atmosphere and contributors to the global carbon cycle. Despite this, we do not yet understand how geomorphological features, themselves continuously reworked by hydrology and sedimentary dynamics, affect CO2 fluxes in streams. We show that gravel bars, clearly conspicuous geomorphological features, are hotspots of CO2 fluxes compared to the streamwater itself. This has major implications for carbon cycling and stream ecosystem functioning. Finally, we discuss what stream management could learn from ecohydraulic insights from young scientists doing excellent basic research.

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...

Heterotrophic bacterioplankton control on organic and inorganic carbon cycle in stratified and non-stratified lakes of NW Russia

NASA Astrophysics Data System (ADS)

Shirokova, Liudmila; Vorobjeva, Taissia; Zabelina, Svetlana; Moreva, Olga; Klimov, Sergey; Shorina, Natalja; Chupakov, Artem; Pokrovsky, Oleg; Audry, Stephan; Viers, Jerome

2010-05-01

Lakes of boreal zone regulate the fate of dissolved carbon, nutrients and trace metals during their transport from the watershed to the ocean. Study of primary production - mineralization processes in the context of carbon biogeochemical cycle allows determination of the rate and mechanisms of phytoplankton biomass production and its degradation via aquatic heterotrophic bacteria. In particular, comparative study of vertical distribution of Dissolved Organic Carbon (DOC) in stratified and non-stratified lakes allows establishing the link between biological and chemical aspects of the carbon cycle which, in turns, determines an environmental stability and recovering potential of the entire ecosystem. In order to better understand the biogeochemical mechanisms that control dissolved organic and inorganic carbon migration in surface boreal waters, we studied in 2007-2009 two strongly stratified lakes (15-20 m deep) and two shallow lakes (2-4 m deep) in the Arkhangelsk region (NW Russia, White Sea basin). We conducted natural experiments of the lake water incubation for measurements of the intensity of production/mineralization processes and we determined vertical concentration of DOC during four basic hydrological seasons (winter and summer stratification, and spring and autumn lake overturn). Our seasonal studies of production/mineralization processes demonstrated high intensity of organic matter formation during summer period and significant retard of these processes during winter stagnation. During spring period, there is a strong increase of bacterial destruction of the allochtonous organic matter that is being delivered to the lake via terrigenous input. During autumn overturn, there is a decrease of the activity of phytoplankton, and the degradation of dead biomass by active bacterial community. Organic matter destruction processes are the most active in Svyatoe lake, whereas in the Beloe lake, the rate of organic matter production is significantly higher than its bacterial degradation, and in the Maselgskoe lake the aerobic mineralization plays insignificant role. Seasonally-stratified lake Svyatoe demonstrates systematic decrease of DOC concentration from the surface to the bottom horizon during summer and winter stagnation, whereas lake Maselgskoe exhibits an increase of DOC in the bottom horizons during winter stratification. During the autumn and spring overturn, we observe rather constant concentration of DOC due to well mixing of the water masses and low activity of the phytoplankton community. Results of the present work allow the evaluation of biotic and abitioc components of the biogeochemical cycle of carbon in small stratified and non-stratified lakes of the Arctic Ocean basin. They allow quantification of the direct link between the processes of primary production/heterotrophic bacteria mineralization and vertical profile of organic and inorganic carbon concentration.

Energy from nuclear fission()

NASA Astrophysics Data System (ADS)

Ripani, M.

2015-08-01

The main features of nuclear fission as physical phenomenon will be revisited, emphasizing its peculiarities with respect to other nuclear reactions. Some basic concepts underlying the operation of nuclear reactors and the main types of reactors will be illustrated, including fast reactors, showing the most important differences among them. The nuclear cycle and radioactive-nuclear-waste production will be also discussed, along with the perspectives offered by next generation nuclear assemblies being proposed. The current situation of nuclear power in the world, its role in reducing carbon emission and the available resources will be briefly illustrated.

Sustainable polymers from renewable resources

NASA Astrophysics Data System (ADS)

Zhu, Yunqing; Romain, Charles; Williams, Charlotte K.

2016-12-01

Renewable resources are used increasingly in the production of polymers. In particular, monomers such as carbon dioxide, terpenes, vegetable oils and carbohydrates can be used as feedstocks for the manufacture of a variety of sustainable materials and products, including elastomers, plastics, hydrogels, flexible electronics, resins, engineering polymers and composites. Efficient catalysis is required to produce monomers, to facilitate selective polymerizations and to enable recycling or upcycling of waste materials. There are opportunities to use such sustainable polymers in both high-value areas and in basic applications such as packaging. Life-cycle assessment can be used to quantify the environmental benefits of sustainable polymers.

Sustainable polymers from renewable resources.

PubMed

Zhu, Yunqing; Romain, Charles; Williams, Charlotte K

2016-12-14

Renewable resources are used increasingly in the production of polymers. In particular, monomers such as carbon dioxide, terpenes, vegetable oils and carbohydrates can be used as feedstocks for the manufacture of a variety of sustainable materials and products, including elastomers, plastics, hydrogels, flexible electronics, resins, engineering polymers and composites. Efficient catalysis is required to produce monomers, to facilitate selective polymerizations and to enable recycling or upcycling of waste materials. There are opportunities to use such sustainable polymers in both high-value areas and in basic applications such as packaging. Life-cycle assessment can be used to quantify the environmental benefits of sustainable polymers.

[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.

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...

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.

Orbitally-Induced, Quasi-Periodic Climate Change on Mars: Modelling Changes in the Global Cycling of Water and Carbon Dioxide

NASA Astrophysics Data System (ADS)

Mischna, M. A.; Richardson, M. I.; Wilson, R. J.

2002-12-01

Mars' orbital parameters (obliquity, eccentricity and argument of perihelion) are thought to have varied substantially on time scales >105 years. Such variations, especially in obliquity, may drastically affect the circulation of the atmosphere and volatile cycling. In this study, we focus on the response of the water and carbon dioxide cycles to changes in these orbital parameters, chiefly obliquity. The study employs the Geophysical Fluid Dynamics Laboratory Mars General Circulation Model, conducting simulations over a range of orbital states to examine changes in the cycling and deposition of these volatiles. This model contains full 3D accounting of atmospheric water and carbon dioxide as well as a basic dust cycle. The present martian obliquity is 25°, though it is believed to have recently varied between 15 and 45 degrees. Our simulations look at present martian conditions, only with obliquity varying between 5 and 60 degrees. Simulations are run out until water and carbon dioxide budgets have reached equilibrium--typically 30-40 years. As expected, volatile cycling on Mars increases with obliquity, as the polar caps are exposed to increased insolation, leading to greater seasonal ice caps and ultimately development of surface water ice in the now thermally favorible low latitudes. By 45°, water ice is stable in a broad band just north of the equator. Such an ice distribution has potential implications for the surface wind pattern through the ice-albedo effect on surface heating. Permanent polar CO2 caps are not stable under present conditions, but we find CO2 cap growth and corresponding atmospheric deflation to be evident at very low obliquities. We find that for most choices of orbital conditions, the northern hemisphere remains the stable pole for water ice, a result of the martian topographic dichotomy. We have begun to look at the impact of desorbed CO2 and H2O ice from the regolith on climatic conditions. Present estimates of the volatile abundance in the regolith vary greatly, but recent Mars Odyssey results hint at large abundances of water ice in the martian high-latitude regolith. The results of this study should better define models of polar volatile evolution, specifically those of layered terrain formation. The radiative feedback effects of increased atmospheric CO2 and H2O from the polar caps and regoliths has yet to be examined. Future plans include more accurate representations of dust injection and radiative transfer to tackle this problem.

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...

Progress and Future Directions in North American Carbon Cycle Science

NASA Astrophysics Data System (ADS)

Michalak, Anna; Huntzinger, Deborah; Shrestha, Gyami

2013-05-01

The North American Carbon Program (NACP) convened its fourth biennial "All Investigators" meeting (AIM4, http://www.nacarbon.org/meeting_2013) to review progress in understanding the dynamics of the carbon cycle of North America and adjacent oceans and to chart a course for a more integrative and holistic approach to future research. The meeting was structured around the six decadal goals outlined in the new "A U.S. Carbon Cycle Science Plan" (Michalak et al., University Corporation for Atmospheric Research, 2011, available at http://www.carboncyclescience.gov) and focused on (1) diagnosis of the atmospheric carbon cycle, (2) drivers of anthropogenic emissions, (3) vulnerability of carbon stocks to change, (4) ecosystem impacts of change, (5) carbon management, and (6) decision support.

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.

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.

Bottom-up assessment of the Net Ecosystem Carbon Balance of Russian forests in 2010 for comparison to Top-down estimates.

NASA Astrophysics Data System (ADS)

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

2014-12-01

The verified full carbon assessment of Russian forests (FCA) is based on an Integrated Land Information System (ILIS) that includes a multi-layer and multi-scale GIS with basic resolution of 1 km and corresponding attributive databases. The ILIS aggregates all available information about ecosystems and landscapes, sets of empirical and semi-empirical data and aggregations, data of different inventories and surveys, and multi-sensor remote sensing data. The ILIS serves as an information base for application of the landscape-ecosystem approach (LEA) of the FCA and as a systems design for comparison and mutual constraints with other methods of study of carbon cycling of forest ecosystems (eddy covariance; process models; inverse modeling; and multi-sensor application of remote sensing). The LEA is based on a complimentary use of the flux-based method with some elements of the pool-based method. Introduction of climatic parameters of individual years in the LEA, as well as some process-based elements, allows providing a substantial decrease of the uncertainties of carbon cycling yearly indicators of forest ecosystems. Major carbon pools (live biomass, coarse woody debris, soil organic carbon) are estimated based on data on areas, distribution and major biometric characteristics of Russian forests presented in form of the ILIS for the country. The major fluxes accounted for include Net Primary Production (NPP), Soil Heterotrophic Respiration (SHR), as well as fluxes caused by decomposition of Coarse Woody Debris (CWD), harvest and use of forest products, fluxes caused by natural disturbances (fire, insect outbreaks, impacts of unfavorable environment) and lateral fluxes to hydrosphere and lithosphere. Use of landscape-ecosystem approach resulted in the NECB at 573±140 Tg C yr-1 (CI 0.9). While the total carbon sink is high, large forest areas, particularly on permafrost, serve as a carbon source. The ratio between net primary production and soil heterotrophic respiration, together with natural and human-induced disturbances are major drivers of the magnitude and spatial distribution of the NECB of forest ecosystems. We also present comparison to the recent top-down estimates of the Siberian carbon sink.

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.

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.

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

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%.

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.

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

Potential for using remote sensing to estimate carbon fluxes across northern peatlands - A review.

PubMed

Lees, K J; Quaife, T; Artz, R R E; Khomik, M; Clark, J M

2018-02-15

Peatlands store large amounts of terrestrial carbon and any changes to their carbon balance could cause large changes in the greenhouse gas (GHG) balance of the Earth's atmosphere. There is still much uncertainty about how the GHG dynamics of peatlands are affected by climate and land use change. Current field-based methods of estimating annual carbon exchange between peatlands and the atmosphere include flux chambers and eddy covariance towers. However, remote sensing has several advantages over these traditional approaches in terms of cost, spatial coverage and accessibility to remote locations. In this paper, we outline the basic principles of using remote sensing to estimate ecosystem carbon fluxes and explain the range of satellite data available for such estimations, considering the indices and models developed to make use of the data. Past studies, which have used remote sensing data in comparison with ground-based calculations of carbon fluxes over Northern peatland landscapes, are discussed, as well as the challenges of working with remote sensing on peatlands. Finally, we suggest areas in need of future work on this topic. We conclude that the application of remote sensing to models of carbon fluxes is a viable research method over Northern peatlands but further work is needed to develop more comprehensive carbon cycle models and to improve the long-term reliability of models, particularly on peatland sites undergoing restoration. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

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 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.

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.

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...

The joint Russia-US-Sweden studies in the East-Siberian Arctic Shelf (ESAS) during the last decade (1999-2009): an overview

NASA Astrophysics Data System (ADS)

Sergienko, Valentin; Shakhova, Natalia; Dudarev, Oleg; Gustafsson, Orjan; Anderson, Leif; Semiletov, Igor

2010-05-01

The Arctic Ocean is surrounded by permafrost, which is being degraded at an increasing rate under conditions of warming which are most pronounced in Siberia and Alaska . A major constraint on our ability to understand linkages between the Arctic Ocean and the global climate system is the scarcity of observational data in the Siberian Arctic marginal seas where major fresh water input and terrestrial CNP fluxes exist. The East-Siberian Sea has never been investigated by modern techniques despite the progress that has been made in new technologies useful for measuring ocean characteristics of interest. In this multi-year international project which joins scientists from 3 nations (Russia-USA-Sweden), and in cooperation with scientists from other countries (UK, Netherlands) we focus on he ESAS which is poorly explored areas located west from the U.S.-Russia boundary. In this report we overview the main field activities and present some results obtained during the last decade (1999-2009). Siberian freshwater discharge to the Arctic Ocean is expected to increase with increasing temperatures, potentially resulting in greater river export of old terrigenous organic carbon to the ocean. We suggest that rivers integrate variability in the components of the hydrometeorological regime, including soil condition, permafrost seasonal thaw, and thermokarst development, all the variables that determine atmospheric and ground water supply for the rivers and chemical weathering in their watershed.. It has been found that 1) carbon dioxide and methane fluxes are significant (and non-counted) components of the carbon cycling in the Arctic Ocean; 2) transport of eroded terrestrial material plays a major role in the accumulation of carbon in the ESAS (Dudarev et al., Gustafsson et al., Vonk et al., Sanchez-Garcia et al., Charkin et al., Semiletov et al., this session) ; 3) the seabed is a major CH4 source over the ESAS (N.Shakhova et al., this session); 3) eroded carbon is biodegradable (all reports, this session); 4) oxidation of eroded carbon onshore and offshore is a strong source of carbon dioxide (Piko et al. and Semiletov et al., this session). Thus studying carbon cycling in the East Siberian Arctic marginal seas has a high scientific priority in order to establish the carbon budget and evaluate the role of the Arctic region in global carbon cycling, especially in the coastal zone where the redistribution of carbon between terrestrial and marine environments occurs and the characteristics of carbon exchange with atmosphere are unknown. Initial scientific plan for the next decade is discussed. This study was supported by the Russian Foundation for Basic Research (since 1994), International (Soros) Scientific Foundation, ISF (1994-1995), Russian Government and ISF (1995), McArthur Foundation (2000-2001), FEBRAS/RAS (since 2003), IARC (since 2001), NSF (since 2003), NOAA (since 2005), SU (since 2007), and Wallenberg Foundation (since 2008).

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

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

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.

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...

Removal of bromide and iodide anions from drinking water by silver-activated carbon aerogels.

PubMed

Sánchez-Polo, M; Rivera-Utrilla, J; Salhi, E; von Gunten, U

2006-08-01

The aim of this study is to analyze the use of Ag-doped activated carbon aerogels for bromide and iodide removal from drinking water and to study how the activation of Ag-doped aerogels affects their behavior. It has been observed that the carbonization treatment and activation process of Ag-doped aerogels increased the surface area value ( [Formula: see text] ), whereas the volume of meso-(V(2)) and macropores (V(3)) decreased slightly. Chemical characterization of the materials revealed that carbonization and especially activation process considerably increased the surface basicity of the sample. Original sample (A) presented acidic surface properties (pH(PZC)=4.5) with 21% surface oxygen, whereas the sample that underwent activation showed mainly basic surface chemical properties (pH(PZC)=9.5) with only 6% of surface oxygen. Carbonization and especially, activation process considerable increased the adsorption capacity of bromide and iodide ions. This would mainly be produced by (i) an increase in the microporosity of the sample, which increases Ag-adsorption sites available to halide anions, and (ii) a rise of the basicity of the sample, which produces an increase in attractive electrostatic interactions between the aerogel surface, positively charged at the working pH (pH(solution)

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.

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)

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...

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.

40 CFR 180.1021 - Copper; exemption from the requirement of a tolerance.

Code of Federal Regulations, 2010 CFR

2010-07-01

.... (2) Basic copper carbonate (malachite) as an algicide or herbicide in impounded and stagnant bodies.... Basic copper carbonate (malachite) 1184-64-1 Copper ammonia complex 16828-95-8 Copper ethylenediamine...

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.

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.

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.

Estimation of the basicity of the donor strength of terminal groups in cationic polymethine dyes

NASA Astrophysics Data System (ADS)

Kachkovsky, Alexey; Obernikhina, Nataliya; Prostota, Yaroslav; Naumenko, Antonina; Melnyk, Dmitriy; Yashchuk, Valeriy

2018-02-01

The well-known conception of the basicity of the terminal groups in the cationic polymethine dyes showing their donor properties is examined (considered) in detail. The various approachs are proposed to quantitative quantum-chemical estimation of a donor strength of the terminal groups in cationic polymethine dyes: shift of the frontier levels upon introducing terminal residues in comparison with unsybstituted polymethine cation; transferring of the electron density from the terminal groups to the polymethine chain and hence manifested itself as a redistribution of total positive charge between molecular fragments; changes of the charge alternation at carbon atoms along the chain. All approach correlate between them and agree with the concept of the basicity as a capability of terminal heterocycles to show its donor properties in the polymethine dyes. The results of the fulfilled calculations of numerous examples are presented; the proposed parameters point correctly the tendency in the change donor strength upon varying of the chemical constitution: the dimension of cycle, introducing of various heteroatoms, linear or angular annelating by benzene ring; as well as direct to take into consideration the existence of local levels.

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.

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...

Newer polyanionic bio-composite anode for sodium ion batteries

NASA Astrophysics Data System (ADS)

Karuppiah, Saravanan; Vellingiri, Suganya; Nallathamby, Kalaiselvi

2017-02-01

NASICON frame work Na3V2(PO4)3 (NVP), wrapped by nitrogen and sulfur doped bio-carbon matrix derived from human hair (HHC) has been investigated for its anode behavior in SIBs. Basically, NVP is bestowed with a crystal structure of 3D open framework and a moderate theoretical capacity of 118 mAh g-1, which are the twin advantages and motivation behind the selection of this material. Prepared through a simple, scalable and facile method, the key problems associated with pristine NVP electrode material, such as inferior conductivity and severe volume change have been mitigated to a great extent through the formation of a composite containing HHC. Herein, HHC is a cheap and eco-friendly composite additive, obtained from a universal bio-waste, viz., human hair and hence NVP/HHC qualifies itself as a green composite. Interestingly, NVP/HHC-10 (in-situ) and NVP/HHC-20 (ex-situ) anodes show excellent electrochemical performance in terms of cycling stability up to 500 cycles and rate capability @ 2 A g-1, which are superior than similar category NVP anodes reported in the literature. Further, post cycling structure and morphology of NVP/HHC composite anodes evidence the appreciable stability bestowed with the select composition, which is found to get maintained upon extended cycles and even after rate capability test.

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.

Biogeochemical Carbon Cycling in Ultrabasic Reducing Springs in Sonoma County, CA

NASA Astrophysics Data System (ADS)

Cotton, J. M.; Morrill, P.; Johnson, O.; Nealson, K. H.; Sherwood Lollar, B.; Eigenbrode, J.; Fogel, M.

2006-12-01

Dissolved gases in the ultrabasic spring waters from The Cedars in Sonoma County, CA were analyzed for concentrations and carbon and hydrogen isotopic ratios in order to determine the geobiological processes occurring in this extreme environment of unknown biological activity. The ultrabasic, highly reducing conditions unique to these springs result from local serpentinization. Gases bubbling from the springs are mainly composed of methane, hydrogen, and nitrogen. Serpentinization is a process characteristic of early Earth, Mars and Titan that is thought to produce abiogenic hydrocarbons as well as provide geochemical energy for chemolithotrophic life. Methane, CO2, hydrogen and nitrogen were detected in the aqueous phases. Earlier work indicated that the primary source of the methane in the free gases bubbling from the springs was associated with microbial fermentation a suspected source of the dissolved methane. Here we report, a negative, linear correlation between concentrations of CO2 and methane that is an indicator of microbial anaerobic methane oxidation taking place in the ultrabasic waters. Furthermore, as the concentrations of methane decrease, the concentration of CO2 increases and both reactant and product become 13C-enriched. These observations are consistent with microbial oxidation of methane, suggesting a biogeochemical carbon cycle exists in these springs. We hypothesize that one group of microbes is breaking down organic matter by a process of fermentation to produce methane and CO2. The CO2 dissolves in the basic springs, while most of the methane escapes solution. The residual dissolved methane undergoes a conversion to CO2 by anaerobic methane oxidation.

Reactivity of zirconium basic sulfate in the reactions with carbonate, oxalate, and phosphate reagents

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

Nekhamkin, L.G.; Kondrashova, I.A.; Kerina, V.R.

1987-08-20

The reactivity of zirconium basic sulfate is determined by the possibility of replacement of oxo- and hydroxo-ligands and decreases with increasing temperature of its precipitation. The interaction of the less reactive zirconium basic sulfate with carbonate and oxalate reagents occurs at 25/sup 0/C without any change in basicity and that with phosphate reagents occurs with a decrease in it, up to the formation of a monophosphate with basicity about 20%. In the interaction of the more reactive zirconium basic sulfate, obtained without heating, oxo- and hydroxo groups can be entirely replaced by acido-ligands with the formation of unhydrolyzed compounds.

Molecular and Microscopic Insights into the Formation of Soil Organic Matter in a Red Pine Rhizosphere

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

Dohnalkova, Alice C.; Tfaily, Malak M.; Smith, A. Peyton

Microbially-derived carbon inputs to soils play an important role in forming soil organic matter (SOM), but detailed knowledge of basic mechanisms of carbon (C) cycling, such as stabilization of organic C compounds originating from rhizodeposition, is scarce. This study aimed to investigate the stability of rhizosphere-produced carbon components in a model laboratory mesocosm of Pinus resinosa grown in a designed mineral soil mix with limited nutrients. We utilized a suite of advanced imaging and molecular techniques to obtain a molecular-level identification of newly-formed SOM compounds, and considered implications regarding their degree of long-term persistence. The microbes in this controlled, nutrient-limitedmore » system, without pre-existing organic matter, produced extracellular polymeric substances that formed associations with nutrient-bearing minerals and contributed to the microbial mineral weathering process. Electron microscopy revealed unique ultrastructural residual signatures of biogenic C compounds, and the increased presence of an amorphous organic phase associated with the mineral phase was evidenced by X-ray diffraction. Here, these findings provide insight into the formation of SOM products in ecosystems, and show that the plant- and microbially-derived material associated with mineral matrices may be important components in current soil carbon models.« less

Molecular and Microscopic Insights into the Formation of Soil Organic Matter in a Red Pine Rhizosphere

DOE PAGES

Dohnalkova, Alice C.; Tfaily, Malak M.; Smith, A. Peyton; ...

2017-08-26

Microbially-derived carbon inputs to soils play an important role in forming soil organic matter (SOM), but detailed knowledge of basic mechanisms of carbon (C) cycling, such as stabilization of organic C compounds originating from rhizodeposition, is scarce. This study aimed to investigate the stability of rhizosphere-produced carbon components in a model laboratory mesocosm of Pinus resinosa grown in a designed mineral soil mix with limited nutrients. We utilized a suite of advanced imaging and molecular techniques to obtain a molecular-level identification of newly-formed SOM compounds, and considered implications regarding their degree of long-term persistence. The microbes in this controlled, nutrient-limitedmore » system, without pre-existing organic matter, produced extracellular polymeric substances that formed associations with nutrient-bearing minerals and contributed to the microbial mineral weathering process. Electron microscopy revealed unique ultrastructural residual signatures of biogenic C compounds, and the increased presence of an amorphous organic phase associated with the mineral phase was evidenced by X-ray diffraction. Here, these findings provide insight into the formation of SOM products in ecosystems, and show that the plant- and microbially-derived material associated with mineral matrices may be important components in current soil carbon models.« less

Degradation of paracetamol by catalytic wet air oxidation and sequential adsorption - Catalytic wet air oxidation on activated carbons.

PubMed

Quesada-Peñate, I; Julcour-Lebigue, C; Jáuregui-Haza, U J; Wilhelm, A M; Delmas, H

2012-06-30

The concern about the fate of pharmaceutical products has raised owing to the increasing contamination of rivers, lakes and groundwater. The aim of this paper is to evaluate two different processes for paracetamol removal. The catalytic wet air oxidation (CWAO) of paracetamol on activated carbon was investigated both as a water treatment technique using an autoclave reactor and as a regenerative treatment of the carbon after adsorption in a sequential fixed bed process. Three activated carbons (ACs) from different source materials were used as catalysts: two microporous basic ACs (S23 and C1) and a meso- and micro-porous acidic one (L27). During the first CWAO experiment the adsorption capacity and catalytic performance of fresh S23 and C1 were higher than those of fresh L27 despite its higher surface area. This situation changed after AC reuse, as finally L27 gave the best results after five CWAO cycles. Respirometry tests with activated sludge revealed that in the studied conditions the use of CWAO enhanced the aerobic biodegradability of the effluent. In the ADOX process L27 also showed better oxidation performances and regeneration efficiency. This different ageing was examined through AC physico-chemical properties. Copyright © 2012 Elsevier B.V. All rights reserved.

Zooxanthellar symbionts shape host sponge trophic status through translocation of carbon.

PubMed

Weisz, Jeremy B; Massaro, Andrew J; Ramsby, Blake D; Hill, Malcolm S

2010-12-01

Sponges belonging to the genus Cliona are common inhabitants of many coral reefs, and as bioeroders, they play an important role in the carbonate cycle of the reef. Several Cliona species maintain intracellular populations of dinoflagellate zooxanthellae (i.e., Symbiodinium spp.), which also form symbioses with a variety of other invertebrates and protists (e.g., corals, molluscs, foraminifera). Unlike the case of coral symbioses, however, almost nothing is known of the metabolic interaction between sponges and their zooxanthella symbionts. To assess this interaction, we performed a tracer experiment to follow C and N in the system, performed a reciprocal transplant experiment, and measured the stable carbon isotope ratio of Cliona spp. with and without zooxanthellae to study the influence of environment on the interaction. We found strong evidence of a transfer of C from zooxanthellae to their sponge hosts but no evidence of a transfer of N from sponge to zooxanthellae. We also saw significant influences of the environment on the metabolism of the sponges. Finally, we observed significant differences in carbon metabolism of sponge species with and without symbionts. These data strongly support hypotheses of metabolic integration between zooxanthellae and their sponge host and extend our understanding of basic aspects of benthic-pelagic coupling in shallow-water marine environments.

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

The HIAPER Pole-to-Pole Observations (HIPPO) Public Data Archive at CDIAC: Carbon Cycle and Greenhouse Gas Data

NASA Astrophysics Data System (ADS)

Christensen, S. W.; Hook, L. A.

2011-12-01

The HIAPER Pole-to-Pole Observations (HIPPO) project is investigating the carbon cycle and greenhouse gases throughout various altitudes in the atmosphere over the Pacific Basin through the annual cycle (Wofsy and the HIPPO Science Team 2011, this session). Aircraft-based data collection occurred during 2009-2011. Data analyses, comparisons, and integration are ongoing. A permanent public archive of HIPPO data has been established at the U. S. DOE Carbon Dioxide Information Analysis Center (CDIAC). Datasets are provided primarily by the Lead Principal Investigator (PI), who draws on a comprehensive set of aircraft navigation information, meteorological measurements, and research instrument and sampling system results from multiple co-investigators to compile integrated and generate value-added products. A website/ftp site has been developed for HIPPO data and metadata (http://hippo.ornl.gov), in coordination with the UCAR website that presents field catalogs and other detailed information about HIPPO missions (http://www.eol.ucar.edu/projects/hippo/dm/). A data policy was adopted that balances the needs of the project investigators with the interests of the scientific user community. A data dictionary was developed to capture the basic characteristics of the hundreds of measurements. Instrument descriptions were compiled. A user's guide is presented for each dataset that also contains data file information enabling users to know when data have been updated. Data are received and provided as space-delimited ASCII files. Metadata records are compiled into a searchable CDIAC index and will be submitted to climate change research data clearinghouses. Each dataset is given a persistent identifier (DOI) to facilitate attribution. We expect that data will continue to be added to the archive for the next year or more. In the future we anticipate creating a database for HIPPO data, with a web interface to facilitate searching and customized data extraction.

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 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.

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.

Carbon-free hydrogen production from low rank coal

NASA Astrophysics Data System (ADS)

Aziz, Muhammad; Oda, Takuya; Kashiwagi, Takao

2018-02-01

Novel carbon-free integrated system of hydrogen production and storage from low rank coal is proposed and evaluated. To measure the optimum energy efficiency, two different systems employing different chemical looping technologies are modeled. The first integrated system consists of coal drying, gasification, syngas chemical looping, and hydrogenation. On the other hand, the second system combines coal drying, coal direct chemical looping, and hydrogenation. In addition, in order to cover the consumed electricity and recover the energy, combined cycle is adopted as addition module for power generation. The objective of the study is to find the best system having the highest performance in terms of total energy efficiency, including hydrogen production efficiency and power generation efficiency. To achieve a thorough energy/heat circulation throughout each module and the whole integrated system, enhanced process integration technology is employed. It basically incorporates two core basic technologies: exergy recovery and process integration. Several operating parameters including target moisture content in drying module, operating pressure in chemical looping module, are observed in terms of their influence to energy efficiency. From process modeling and calculation, two integrated systems can realize high total energy efficiency, higher than 60%. However, the system employing coal direct chemical looping represents higher energy efficiency, including hydrogen production and power generation, which is about 83%. In addition, optimum target moisture content in drying and operating pressure in chemical looping also have been defined.

Strategies for emission reduction from thermal power plants.

PubMed

Prisyazhniuk, Vitaly A

2006-07-01

Major polluters of man's environment are thermal power stations (TPS) and power plants, which discharge into the atmosphere the basic product of carbon fuel combustion, CO2, which results in a build-up of the greenhouse effect and global warm-up of our planet's climate. This paper is intended to show that the way to attain environmental safety of the TPS and to abide by the decisions of the Kyoto Protocol lies in raising the efficiency of the heat power stations and reducing their fuel consumption by using nonconventional thermal cycles. Certain equations have been derived to define the quantitative interrelationship between the growth of efficiency of the TPS, decrease in fuel consumption and reduction of discharge of dust, fuel combustion gases, and heat into the environment. New ideas and new technological approaches that result in raising the efficiency of the TPS are briefly covered: magneto-hydrodynamic resonance, the Kalina cycle, and utilizing the ambient heat by using, as the working medium, low-boiling substances.

Control of Methane Production and Exchange in Northern Peatlands

NASA Technical Reports Server (NTRS)

Crill, Patrick

1997-01-01

This proposal has successfully supported studies that have developed unique long ten-n datasets of methane (CH4) emissions and carbon dioxide (CO2) exchange in order to quantify the controls on CH4 production and exchange especially the linkages to the carbon cycle in northern peatlands. The primary research site has been a small fen in southeastern New Hampshire where a unique multi-year data baseline of CH4 flux measurements was begun (with NASA funding) in 1989. The fen has also been instrumented for continuous hydrological and meteorological observations and year-round porewater sampling. Multiyear datasets of methane flux are very valuable and very rare. Datasets using the same sampling techniques at the same sites are the only way to assess the effect of the integrated ecosystem response to climatological variability. The research has had two basic objectives: 1. To quantify the effect of seasonal and interannual variability on CH4flux. 2. To examine process level controls on methane dynamics.

EFFECTS OF TEMPERATURE AND ENVIRONMENT ON MECHANICAL PROPERTIES OF TWO CHOPPED-FIBER AUTOMOTIVE STRUCTURAL COMPOSITES

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

Ruggles-Wrenn, M.B.

2003-10-06

The Durability of Lightweight Composite Structures Project was established at Oak Ridge National Laboratory (ORNL) by the U.S. Department of Energy to provide the experimentally-based, durability-driven design guidelines necessary to assure long-term structural integrity of automotive composite components. The initial focus of the ORNL Durability Project was on composite materials consisting of polyurethane reinforced with E-glass. Current focus of the project is on composite materials reinforced with carbon fibers. The primary purpose of this report is to provide the individual specimen test date. Basic mechanical property testing and results for two chopped-fiber composite materials, one reinforced with glass- and themore » other with carbon fiber are provided. Both materials use the same polyurethane matrix. Preforms for both materials were produced using the P4 process. Behavioral trends, effects of temperature and environment, and corresponding design knockdown factors are established for both materials. Effects of prior short-time loads and of prior thermal cycling are discussed.« less

Power-to-Syngas: An Enabling Technology for the Transition of the Energy System?

PubMed

Foit, Severin R; Vinke, Izaak C; de Haart, Lambertus G J; Eichel, Rüdiger-A

2017-05-08

Power-to-X concepts promise a reduction of greenhouse gas emissions simultaneously guaranteeing a safe energy supply even at high share of renewable power generation, thus becoming a cornerstone of a sustainable energy system. Power-to-syngas, that is, the electrochemical conversion of steam and carbon dioxide with the use of renewably generated electricity to syngas for the production of synfuels and high-value chemicals, offers an efficient technology to couple different energy-intense sectors, such as "traffic and transportation" and "chemical industry". Syngas produced by co-electrolysis can thus be regarded as a key-enabling step for a transition of the energy system, which offers additionally features of CO 2 -valorization and closed carbon cycles. Here, we discuss advantages and current limitations of low- and high-temperature co-electrolysis. Advances in both fundamental understanding of the basic reaction schemes and stable high-performance materials are essential to further promote co-electrolysis. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

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.

Mexican forest inventory expands continental carbon monitoring

Treesearch

Alberto Sandoval Uribe; Sean. P. Healey; Gretchen G. Moisen; Rigoberto Palafox Rivas; Enrique Gonzalez Aguilar; Carmen Lourdes Meneses Tovar; Ernesto S. Diaz Ponce Davalos; Vanessa Silva Mascorro

2008-01-01

The terrestrial ecosystems of the North American continent represent a large reservoir of carbon and a potential sink within the global carbon cycle. The recent State of the Carbon Cycle Report [U.S. Climate Change Science Program (CCSP), 2007] identified the critical role these systems may play in mitigating effects of greenhouse gases emitted from fossil fuel...

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...

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

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.

Integrative molecular and microanalytical studies of syntrophic partnerships linking C, S, and N cycles in anoxic environments

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

Orphan, Victoria

2016-07-15

Syntrophy and other forms of symbiotic associations between microorganisms are central to carbon and nutrient cycling in the environment. However, the inherent interdependence of these interactions, dynamic behavior, and frequent existence at thermodynamic limits has hindered our ability to both recognize syntrophic partnerships in nature and effectively study their behavior in the laboratory. To characterize and understand the underlying factors influencing syntrophic associations within complex communities requires a suite of tools that extend beyond basic molecular identification and cultivation. This specifically includes methods that preserve the natural spatial relationships between metabolically interdependent microorganisms while allowing downstream geochemical and/or molecular analysis.more » With support from this award, we have developed and applied new combinations of molecular, microscopy, and stable isotope-based methodologies that enable the characterization of fundamental links between phylogenetically-identified microorganisms and their specific metabolic activities and interactions in the environment. Through the coupling of fluorescence in situ hybridization (FISH) with cell capture and targeted metagenomics (Magneto-FISH), and FISH + secondary ion mass spectrometry (i.e. FISH-SIMS or FISH-nanoSIMS), we have defined new microbial interactions and the ecophysiology of anaerobic microorganisms involved in environmental methane cycling.« less

SNTP propellant management system

NASA Technical Reports Server (NTRS)

Tippetts, Tom

1993-01-01

Viewgraphs on the following are presented: (1) space nuclear thermal propulsion (SNTP) propellant management system; (2) SNTP cycle selection; (3) NTP system components unique design constraints; (4) bleed cycle unique design requirement for turbopump; (5) bleed cycle turbopump; (6) SNTP carbon-carbon turbine wheel; and (7) turbine development program.

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.

Dual-objective optimization of organic Rankine cycle (ORC) systems using genetic algorithm: a comparison between basic and recuperative cycles

NASA Astrophysics Data System (ADS)

Hayat, Nasir; Ameen, Muhammad Tahir; Tariq, Muhammad Kashif; Shah, Syed Nadeem Abbas; Naveed, Ahmad

2017-08-01

Exploitation of low potential waste thermal energy for useful net power output can be done by manipulating organic Rankine cycle systems. In the current article dual-objectives (η_{th} and SIC) optimization of ORC systems [basic organic Rankine cycle (BORC) and recuperative organic Rankine cycle (RORC)] has been done using non-dominated sorting genetic algorithm (II). Seven organic compounds (R-123, R-1234ze, R-152a, R-21, R-236ea, R-245ca and R-601) have been employed in basic cycle and four dry compounds (R-123, R-236ea, R-245ca and R-601) have been employed in recuperative cycle to investigate the behaviour of two systems and compare their performance. Sensitivity analyses show that recuperation boosts the thermodynamic behaviour of systems but it also raises specific investment cost significantly. R-21, R-245ca and R-601 show attractive performance in BORC whereas R-601 and R-236ea in RORC. RORC, due to higher total investment cost and operation & maintenance costs, has longer payback periods as compared to BORC.

Cycle simulation of the low-temperature triple-effect absorption chiller with vapor compression unit

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

Kim, J.S.; Lee, H.

1999-07-01

The construction of a triple-effect absorption chiller machine using the lithium bromide-water solution as a working fluid is strongly limited by corrosion problems caused by the high generator temperature. In this work, three new cycles having the additional vapor compression units were suggested in order to lower the generator temperature of a triple-effect absorption chiller. Each new cycle has one compressor located at the different position which was used to elevate the pressure of the refrigerant vapor. Computer simulations were carried out in order to examine both the basic triple-effect cycle and three new cycles. All types of triple-effect absorptionmore » chiller cycles were found to be able to lower the temperature of high-temperature generator to the more favorable operation range. The COPs of three cycles calculated by considering the additional compressor works showed a small level of decrease or increase compared with that of the basic triple-effect cycle. Consequently, a low-temperature triple-effect absorption chiller can be possibly constructed by adapting one of three new cycles. A great advantage of these new cycles over the basic one is that the conventionally used lithium bromide-water solution can be successfully used as a working fluid without the danger of corrosion.« less

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.

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

Using the adsorption chillers for waste heat utilisation from the CCS installation

NASA Astrophysics Data System (ADS)

Sztekler, Karol; Kalawa, Wojciech; Nowak, Wojciech; Stefański, Sebastian; Krzywański, Jarosław; Grabowska, Karolina

2018-06-01

Worldwide tendencies in the scope of environmental protection demonstrate the requirement for the limited carbon dioxide emission, that influences on the development of greenhouse effect. As a result of coal as a basic fuel used in the professional power industry, this industry sector is the greatest CO2 polluter and it means that works on the reduction of carbon dioxide in such industry are completely justified. In the IPSEpro programming environment, a reference block model for a conventional coal power station was elaborated, including the CO2 separation unit basing on the adsorption methods with the CO2 preparation installation to liquid state. Simulation researches were conducted with means of numeric techniques, that enabled the system analysis for the CO2 separation unit with the CO2 preparation system to the liquid state, as well as analysis was made for the use of chiller systems, basing on the adsorption technology for waste heat use originating from the compression of CO2 in a cascade system, as well as for potential opportunities for further exploitation of the produced chilled water in the CCS cycle. We analysed in these papers the opportunities for chiller systems application, based on the adsorption chillers in the CCS installation used for the reduction of CO2 emission in the coal power station and its influence on the operation of a power station cycle.

Layer-by-Layer Assembled Architecture of Polyelectrolyte Multilayers and Graphene Sheets on Hollow Carbon Spheres/Sulfur Composite for High-Performance Lithium-Sulfur Batteries.

PubMed

Wu, Feng; Li, Jian; Su, Yuefeng; Wang, Jing; Yang, Wen; Li, Ning; Chen, Lai; Chen, Shi; Chen, Renjie; Bao, Liying

2016-09-14

In the present work, polyelectrolyte multilayers (PEMs) and graphene sheets are applied to sequentially coat on the surface of hollow carbon spheres/sulfur composite by a flexible layer-by-layer (LBL) self-assembly strategy. Owing to the strong electrostatic interactions between the opposite charged materials, the coating agents are very stable and the coating procedure is highly efficient. The LBL film shows prominent impact on the stability of the cathode by acting as not only a basic physical barrier, and more importantly, an ion-permselective film to block the polysulfides anions by Coulombic repulsion. Furthermore, the graphene sheets can help to stabilize the polyelectrolytes film and greatly reduce the inner resistance of the electrode by changing the transport of the electrons from a "point-to-point" mode to a more effective "plane-to-point'' mode. On the basis of the synergistic effect of the PEMs and graphene sheets, the fabricated composite electrode exhibits very stable cycling stability for over 200 cycles at 1 A g(-1), along with a high average Coulombic efficiency of 99%. With the advantages of rapid and controllable fabrication of the LBL coating film, the multifunctional architecture developed in this study should inspire the design of other lithium-sulfur cathodes with unique physical and chemical properties.

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...

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.

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

Small Engine Repair. Two-Stroke and Four-Stroke Cycle.

ERIC Educational Resources Information Center

Hires, Bill; And Others

This curriculum guide is intended to assist persons teaching a course in repairing two- and four-stroke cycle small engines. Addressed in the individual units of instruction are the following topics: safety, tools, fasteners, and measurement techniques; basic small engine theory (engine identification and inspection, basic engine principles and…

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.

Rethinking the Role of Salps in the Ocean.

PubMed

Henschke, Natasha; Everett, Jason D; Richardson, Anthony J; Suthers, Iain M

2016-09-01

Salps are barrel-shaped, gelatinous zooplankton that regularly form large swarms. They have historically been ignored because they are difficult to sample and their gelatinous body structure suggests that they are unimportant in food webs and biogeochemical cycles. We collate evidence to overturn several common misconceptions about salps that have hampered research. We show that salps play a major role in carbon sequestration and are key components of marine food webs as a food source for at least 202 species including fish, turtles, and crustaceans. The future of salps in the Anthropocene is uncertain, and therefore further research into areas such as basic rate processes and their biogeochemical impact through new and innovative laboratory and field methods is needed. Copyright © 2016 Elsevier Ltd. All rights reserved.

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

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.

Processes regulating progressive nitrogen limitation under elevated carbon dioxide: a meta-analysis

NASA Astrophysics Data System (ADS)

Liang, Junyi; Qi, Xuan; Souza, Lara; Luo, Yiqi

2016-05-01

The nitrogen (N) cycle has the potential to regulate climate change through its influence on carbon (C) sequestration. Although extensive research has explored whether or not progressive N limitation (PNL) occurs under CO2 enrichment, a comprehensive assessment of the processes that regulate PNL is still lacking. Here, we quantitatively synthesized the responses of all major processes and pools in the terrestrial N cycle with meta-analysis of CO2 experimental data available in the literature. The results showed that CO2 enrichment significantly increased N sequestration in the plant and litter pools but not in the soil pool, partially supporting one of the basic assumptions in the PNL hypothesis that elevated CO2 results in more N sequestered in organic pools. However, CO2 enrichment significantly increased the N influx via biological N fixation and the loss via N2O emission, but decreased the N efflux via leaching. In addition, no general diminished CO2 fertilization effect on plant growth was observed over time up to the longest experiment of 13 years. Overall, our analyses suggest that the extra N supply by the increased biological N fixation and decreased leaching may potentially alleviate PNL under elevated CO2 conditions in spite of the increases in plant N sequestration and N2O emission. Moreover, our syntheses indicate that CO2 enrichment increases soil ammonium (NH4+) to nitrate (NO3-) ratio. The changed NH4+/NO3- ratio and subsequent biological processes may result in changes in soil microenvironments, above-belowground community structures and associated interactions, which could potentially affect the terrestrial biogeochemical cycles. In addition, our data synthesis suggests that more long-term studies, especially in regions other than temperate ones, are needed for comprehensive assessments of the PNL hypothesis.

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.

Mathematical modeling of the central carbohydrate metabolism in Arabidopsis reveals a substantial regulatory influence of vacuolar invertase on whole plant carbon metabolism.

PubMed

Nägele, Thomas; Henkel, Sebastian; Hörmiller, Imke; Sauter, Thomas; Sawodny, Oliver; Ederer, Michael; Heyer, Arnd G

2010-05-01

A mathematical model representing metabolite interconversions in the central carbohydrate metabolism of Arabidopsis (Arabidopsis thaliana) was developed to simulate the diurnal dynamics of primary carbon metabolism in a photosynthetically active plant leaf. The model groups enzymatic steps of central carbohydrate metabolism into blocks of interconverting reactions that link easily measurable quantities like CO(2) exchange and quasi-steady-state levels of soluble sugars and starch. When metabolite levels that fluctuate over diurnal cycles are used as a basic condition for simulation, turnover rates for the interconverting reactions can be calculated that approximate measured metabolite dynamics and yield kinetic parameters of interconverting reactions. We used experimental data for Arabidopsis wild-type plants, accession Columbia, and a mutant defective in vacuolar invertase, AtbetaFruct4, as input data. Reducing invertase activity to mutant levels in the wild-type model led to a correct prediction of increased sucrose levels. However, additional changes were needed to correctly simulate levels of hexoses and sugar phosphates, indicating that invertase knockout causes subsequent changes in other enzymatic parameters. Reduction of invertase activity caused a decline in photosynthesis and export of reduced carbon to associated metabolic pathways and sink organs (e.g. roots), which is in agreement with the reported contribution of vacuolar invertase to sink strength. According to model parameters, there is a role for invertase in leaves, where futile cycling of sucrose appears to have a buffering effect on the pools of sucrose, hexoses, and sugar phosphates. Our data demonstrate that modeling complex metabolic pathways is a useful tool to study the significance of single enzyme activities in complex, nonintuitive networks.

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.

Catalytic transformations of biomass substrates using mixed metal oxides derived from substituted hydrotalcites

NASA Astrophysics Data System (ADS)

Macala, Gerald Stephen, II

Fueled by seemingly endless reserves of cheap and easily accessible fossil energy, the industrial age has brought to the developed world tremendous advances in human health and well being. Unfortunately the burning of fossil fuels has also been implicated in increasing atmospheric CO2 concentrations and global climate change. Concerns about short-term and long-term supply further build a case for the need for alternative energy sources. Biomass derived materials are a tantalizing source of fuels and fine chemicals. Unlike petroleum derived hydrocarbons, biomass can be both renewable and carbon neutral. Crops can be regenerated annually or even more often in tropical climates, and since the captured carbon originates as atmospheric CO2, the overall cycle has the potential to be nearly carbon neutral regardless of the final fate of the carbon. In contrast to petroleum derived hydrocarbons, which can often be made more valuable by adding functionality, biomass derived materials are already highly functionalized and can usually be made more valuable by selective removal of functionality. The development of robust catalysts capable of selective defuntionalization of biomass derived substrates remains an important challenge with potentially enormous economic and societal impact. In addition to being robust and selective, catalysts should preferably be heterogeneous to allow for easier removal and regeneration after the reaction is complete. New materials consisting of Mg-Al hydrotalcite-like structures, with a limiting percentage of Mg or Al substituted with other M2+ or M3+ cations, were synthesized by a co-precipitation process in basic aqueous solution with carbonate as counterion. Calcination of these materials at 460 °C resulted in evolution of CO2 and water and yielded high surface area mixed metal oxides with enhanced reactivity. Materials were characterized by ICP for elemental analysis, XRD for structural information, XPS for surface elemental analysis and TEM for morphology. Substituting some of the Al for ferric ion resulted in enhanced basicity and enhanced reactivity towards transesterification of seed oil and the model compound triacetin. Substituting some of the Mg for cupric ion resulted in a transfer hydrogenation catalyst capable of single pot dehydrogenation of methanol and hydrogenation of the model compound dihydrobenzofuran.

Regional variation in the biogeochemical and physical characteristics of natural peatland pools.

PubMed

Turner, T Edward; Billett, Michael F; Baird, Andy J; Chapman, Pippa J; Dinsmore, Kerry J; Holden, Joseph

2016-03-01

Natural open-water pools are a common feature of northern peatlands and are known to be an important source of atmospheric methane (CH4). Pool environmental variables, particularly water chemistry, vegetation community and physical characteristics, have the potential to exert strong controls on carbon cycling in pools. A total of 66 peatland pools were studied across three regions of the UK (northern Scotland, south-west Scotland, and Northern Ireland). We found that within-region variability of pool water chemistry was low; however, for many pool variables measured there were significant differences between regions. PCA analysis showed that pools in SW Scotland were strongly associated with greater vegetative cover and shallower water depth which is likely to increase dissolved organic carbon (DOC) mineralisation rates, whereas pools in N Scotland were more open and deeper. Pool water DOC, particulate organic carbon and dissolved CH4 concentrations were significantly different between regions. Pools in Northern Ireland had the highest concentrations of DOC (mean=14.5 mg L(-1)) and CH4 (mean=20.6 μg C L(-1)). Chloride and sulphate concentrations were significantly higher in the pools in N Scotland (mean values 26.3 and 2.40 mg L(-1), respectively) than elsewhere, due to a stronger marine influence. The ratio of UV absorbance at 465 nm to absorbance at 665 nm for pools in Northern Ireland indicated that DOC was sourced from poorly humified peat, potentially increasing the bioavailability and mineralisation of organic carbon in pools compared to the pools elsewhere. This study, which specifically aims to address a lack of basic biogeochemical knowledge about pool water chemistry, clearly shows that peatland pools are highly regionally variable. This is likely to be a reflection of significant regional-scale differences in peatland C cycling. Copyright © 2015 Elsevier B.V. All rights reserved.

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.

Desired crystal oriented LiFePO4 nanoplatelets in situ anchored on a graphene cross-linked conductive network for fast lithium storage.

PubMed

Wang, Bo; Liu, Anmin; Abdulla, Wael Al; Wang, Dianlong; Zhao, X S

2015-05-21

Electron transfer and lithium ion diffusion rates are the key factors limiting the lithium ion storage in anisotropic LiFePO4 electrodes. In this work, we employed a facile solvothermal method to synthesize a "platelet-on-sheet" LiFePO4/graphene composite (LFP@GNs), which is LiFePO4 nanoplatelets in situ grown on graphene sheets with highly oriented (010) facets of LiFePO4 crystals. Such a two-phase contact mode with graphene sheets cross-linked to form a three-dimensional porous network is favourable for both fast lithium ion and electron transports. As a result, the designed LFP@GNs displayed a high rate capability (∼56 mA h g(-1) at 60 C) and long life cycling stability (∼87% capacity retention over 1000 cycles at 10 C). For comparison purposes, samples ex situ modified with graphene (LFP/GNs) as well as pure LiFePO4 platelets (LFP) were also prepared and investigated. More importantly, the obtained LFP@GNs can be used as a basic unit for constructing more complex structures to further improve electrochemical performance, such as coating the exposed LFP surface with a thin layer of carbon to build a C@LFP@GN composite to further enhance its cycling stability (∼98% capacity retention over 1000 cycles at 10 C).

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.

Evaluation of coral reef carbonate production models at a global scale

NASA Astrophysics Data System (ADS)

Jones, N. S.; Ridgwell, A.; Hendy, E. J.

2015-03-01

Calcification by coral reef communities is estimated to account for half of all carbonate produced in shallow water environments and more than 25% of the total carbonate buried in marine sediments globally. Production of calcium carbonate by coral reefs is therefore an important component of the global carbon cycle; it is also threatened by future global warming and other global change pressures. Numerical models of reefal carbonate production are needed for understanding how carbonate deposition responds to environmental conditions including atmospheric CO2 concentrations in the past and into the future. However, before any projections can be made, the basic test is to establish model skill in recreating present-day calcification rates. Here we evaluate four published model descriptions of reef carbonate production in terms of their predictive power, at both local and global scales. We also compile available global data on reef calcification to produce an independent observation-based data set for the model evaluation of carbonate budget outputs. The four calcification models are based on functions sensitive to combinations of light availability, aragonite saturation (Ωa) and temperature and were implemented within a specifically developed global framework, the Global Reef Accretion Model (GRAM). No model was able to reproduce independent rate estimates of whole-reef calcification, and the output from the temperature-only based approach was the only model to significantly correlate with coral-calcification rate observations. The absence of any predictive power for whole reef systems, even when consistent at the scale of individual corals, points to the overriding importance of coral cover estimates in the calculations. Our work highlights the need for an ecosystem modelling approach, accounting for population dynamics in terms of mortality and recruitment and hence calcifier abundance, in estimating global reef carbonate budgets. In addition, validation of reef carbonate budgets is severely hampered by limited and inconsistent methodology in reef-scale observations.

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.

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.

Respiration of the external mycelium in the arbuscular mycorrhizal symbiosis shows strong dependence on recent photosynthates and acclimation to temperature.

PubMed

Heinemeyer, A; Ineson, P; Ostle, N; Fitter, A H

2006-01-01

* Although arbuscular mycorrhizal (AM) fungi are a major pathway in the global carbon cycle, their basic biology and, in particular, their respiratory response to temperature remain obscure. * A pulse label of the stable isotope (13)C was applied to Plantago lanceolata, either uninoculated or inoculated with the AM fungus Glomus mosseae. The extra-radical mycelium (ERM) of the fungus was allowed to grow into a separate hyphal compartment excluding roots. We determined the carbon costs of the ERM and tested for a direct temperature effect on its respiration by measuring total carbon and the (13)C:(12)C ratio of respired CO(2). With a second pulse we tested for acclimation of ERM respiration after 2 wk of soil warming. * Root colonization remained unchanged between the two pulses but warming the hyphal compartment increased ERM length. delta(13)C signals peaked within the first 10 h and were higher in mycorrhizal treatments. The concentration of CO(2) in the gas samples fluctuated diurnally and was highest in the mycorrhizal treatments but was unaffected by temperature. Heating increased ERM respiration only after the first pulse and reduced specific ERM respiration rates after the second pulse; however, both pulses strongly depended on radiation flux. * The results indicate a fast ERM acclimation to temperature, and that light is the key factor controlling carbon allocation to the fungus.

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

The 2nd State of the Carbon Cycle Report (SOCCR-2): Process, Progress and Institutional Context

NASA Astrophysics Data System (ADS)

Shrestha, G.; Cavallaro, N.; Zhu, Z.; Larson, E. K.; Butler, J. H.

2017-12-01

Over 200 scientists and program managers from U.S., Mexican and Canadian government and non-government institutions have been collaborating on SOCCR-2 since 2015. Responding to the U.S. Global Change Research Act (1990) and the U.S. Carbon Cycle Science Plan (2011), this special Sustained National Climate Assessment report covers many of the GCRA mandated sectors such as agriculture, energy, forestry, aquatic systems, coasts, wetlands, atmospheric and human social systems, integrating the scientific uncertainties and analyzing the effects of global change on the carbon cycle and vice versa, including projections for both human- induced and natural changes. This presentation covers the SOCCR-2 process, progress and institutional context, providing a historical perspective on the interagency instruments and mechanisms that have facilitated the last decades of carbon cycle science reflected in SOCCR-2.

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

The Earth System Science Pathfinder Orbiting Carbon Observatory (OCO) Mission

NASA Technical Reports Server (NTRS)

Crisp, David

2003-01-01

A viewgraph presentation describing the Earth System Science Pathfinder Orbiting Carbon Observatory (OCO) Mission is shown. The contents include: 1) Why CO2?; 2) What Processes Control CO2 Sinks?; 3) OCO Science Team; 4) Space-Based Measurements of CO2; 5) Driving Requirement: Precise, Bias-Free Global Measurements; 6) Making Precise CO2 Measurements from Space; 7) OCO Spatial Sampling Strategy; 8) OCO Observing Modes; 9) Implementation Approach; 10) The OCO Instrument; 11) The OCO Spacecraft; 12) OCO Will Fly in the A-Train; 13) Validation Program Ensures Accuracy and Minimizes Spatially Coherent Biases; 14) Can OCO Provide the Required Precision?; 15) O2 Column Retrievals with Ground-based FTS; 16) X(sub CO2) Retrieval Simulations; 17) Impact of Albedo and Aerosol Uncertainty on X(sub CO2) Retrievals; 18) Carbon Cycle Modeling Studies: Seasonal Cycle; 19) Carbon Cycle Modeling Studies: The North-South Gradient in CO2; 20) Carbon Cycle Modeling Studies: Effect of Diurnal Biases; 21) Project Status and Schedule; and 22) Summary.

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.

The sleep-wake-cycle: basic mechanisms.

PubMed

Jones, B E

1989-11-01

The physiologic characteristics of the sleep-wake states have been well defined and some of the chemical and neuron systems that participate in the cyclic generation and maintenance of these states have been identified. The actual dynamic process by which these systems interact to generate the basic sleep-wake cycle, however, remains a mystery.

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.

Adsorption of basic Red 46 using sea mango (Cerbera odollam) based activated carbon

NASA Astrophysics Data System (ADS)

Azmi, Nur Azira Iqlima; Zainudin, Nor Fauziah; Ali, Umi Fazara Md

2015-05-01

Sea mango or Cerbera Odollam is another source of carbonaceous material that can be found abundantly in Malaysia. In this research, it is used as a new agricultural source of activated carbon. Sea mango activated carbon was prepared by chemical activation using potassium hydroxide (KOH). The sea mango was soaked in KOH at impregnation ratio of 1:1 and followed by carbonization at temperature of 600°C for 1 hour. The sample was then characterized using Scanning Electron Microscope (SEM) for surface morphology, while Brunauer-Emmett-Teller (BET) was used to study the surface area. The result shown that sea mango activated carbon (SMAC) developed new pores on its surface and the BET surface area measured was 451.87 m2/g. The SMAC performance was then tested for the removal of Basic Red 46 in batch process. The removal of Basic Red 46 (50 mg/L, natural pH, 0.1 g SMAC) was more than 99% in 15 minutes where it reached equilibrium in 30 minutes.

Using a software-defined computer in teaching the basics of computer architecture and operation

NASA Astrophysics Data System (ADS)

Kosowska, Julia; Mazur, Grzegorz

2017-08-01

The paper describes the concept and implementation of SDC_One software-defined computer designed for experimental and didactic purposes. Equipped with extensive hardware monitoring mechanisms, the device enables the students to monitor the computer's operation on bus transfer cycle or instruction cycle basis, providing the practical illustration of basic aspects of computer's operation. In the paper, we describe the hardware monitoring capabilities of SDC_One and some scenarios of using it in teaching the basics of computer architecture and microprocessor operation.

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.

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.

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.

A general strategy toward graphitized carbon coating on iron oxides as advanced anodes for lithium-ion batteries.

PubMed

Ding, Chunyan; Zhou, Weiwei; Wang, Bin; Li, Xin; Wang, Dong; Zhang, Yong; Wen, Guangwu

2017-08-25

Integration of carbon materials with benign iron oxides is blazing a trail in constructing high-performance anodes for lithium-ion batteries (LIBs). In this paper, a unique general, simple, and controllable strategy is developed toward in situ uniform coating of iron oxide nanostructures with graphitized carbon (GrC) layers. The basic synthetic procedure only involves a simple dip-coating process for the loading of Ni-containing seeds and a subsequent Ni-catalyzed chemical vapor deposition (CVD) process for the growth of GrC layers. More importantly, the CVD treatment is conducted at a quite low temperature (450 °C) and with extremely facile liquid carbon sources consisting of ethylene glycol (EG) and ethanol (EA). The GrC content of the resulting hybrids can be controllably regulated by altering the amount of carbon sources. The electrochemical results reveal remarkable performance enhancements of iron oxide@GrC hybrids compared with pristine iron oxides in terms of high specific capacity, excellent rate and cycling performance. This can be attributed to the network-like GrC coating, which can improve not only the electronic conductivity but also the structural integrity of iron oxides. Moreover, the lithium storage performance of samples with different GrC contents is measured, manifesting that optimized electrochemical property can be achieved with appropriate carbon content. Additionally, the superiority of GrC coating is demonstrated by the advanced performance of iron oxide@GrC compared with its corresponding counterpart, i.e., iron oxides with amorphous carbon (AmC) coating. All these results indicate the as-proposed protocol of GrC coating may pave the way for iron oxides to be promising anodes for LIBs.

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.

Use of Landsat-based monitoring of forest change to sample and assess the role of disturbance and regrowth in the carbon cycle at continental scales

Treesearch

Warren B. Cohen; Sean P. Healey; Samuel Goward; Gretchen G. Moisen; Jeffrey G. Masek; Robert E. Kennedy; Scott L. Powell; Chengquan Huang; Nancy Thomas; Karen Schleeweis; Michael A. Wulder

2007-01-01

The exchange of carbon between forests and the atmosphere is a function of forest type, climate, and disturbance history, with previous studies illustrating that forests play a key role in the terrestrial carbon cycle. The North American Carbon Program (NACP) has supported the acquisition of biennial Landsat image time-series for sample locations throughout much of...

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...

Investigators share improved understanding of the North American carbon cycle

Treesearch

Richard A. Birdsey; Robert Cook; Scott Denning; Peter Griffith; Beverly Law; Jeffrey Masek; Anna Michalak; Stephen Ogle; Dennis Ojima; Yude Pan; Christopher Sabine; Edwin Sheffner; Eric Sundquist

2007-01-01

The U.S. North American Carbon Program (NACP) sponsored an "all-scientist" meeting to review progress in understanding the dynamics of the carbon cycle of North American and adjacent oceans, and to chart a course for improved integration across scientifi c disciplines, scales, and Earth system boundaries. The meeting participants also addressed the need for...

Carbon cycle observations: gaps threaten climate mitigation policies

Treesearch

Richard Birdsey; Nick Bates; MIke Behrenfeld; Kenneth Davis; Scott C. Doney; Richard Feely; Dennis Hansell; Linda Heath; et al.

2009-01-01

Successful management of carbon dioxide (CO2) requires robust and sustained carbon cycle observations. Yet key elements of a national observation network are lacking or at risk. A U.S. National Research Council review of the U.S. Climate Change Science Program earlier this year highlighted the critical need for a U.S. climate observing system to...

Guidelines for Measuring Changes in Seawater pH and Associated Carbonate Chemistry in Coastal Environments of the Eastern United States

EPA Science Inventory

This report begins with descriptions of the differences between coastal and ocean acidification, factors contributing to acidification on the US east coast, and basic characteristics of the seawater carbonate system and its parameters. A basic survey of available methods and cha...

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.

Carbohydrate and energy-yielding metabolism in non-conventional yeasts.

PubMed

Flores, C L; Rodríguez, C; Petit, T; Gancedo, C

2000-10-01

Sugars are excellent carbon sources for all yeasts. Since a vast amount of information is available on the components of the pathways of sugar utilization in Saccharomyces cerevisiae it has been tacitly assumed that other yeasts use sugars in the same way. However, although the pathways of sugar utilization follow the same theme in all yeasts, important biochemical and genetic variations on it exist. Basically, in most non-conventional yeasts, in contrast to S. cerevisiae, respiration in the presence of oxygen is prominent for the use of sugars. This review provides comparative information on the different steps of the fundamental pathways of sugar utilization in non-conventional yeasts: glycolysis, fermentation, tricarboxylic acid cycle, pentose phosphate pathway and respiration. We consider also gluconeogenesis and, briefly, catabolite repression. We have centered our attention in the genera Kluyveromyces, Candida, Pichia, Yarrowia and Schizosaccharomyces, although occasional reference to other genera is made. The review shows that basic knowledge is missing on many components of these pathways and also that studies on regulation of critical steps are scarce. Information on these points would be important to generate genetically engineered yeast strains for certain industrial uses.

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 basic features of a closed fuel cycle without fast reactors

NASA Astrophysics Data System (ADS)

Bobrov, E. A.; Alekseev, P. N.; Teplov, P. S.

2017-01-01

In this paper the basic features of a closed fuel cycle with thermal reactors are considered. The three variants of multiple Pu and U recycling in VVER reactors was investigated. The comparison of MOX and REMIX fuel approaches for closed fuel cycle with thermal reactors is presented. All variants make possible to recycle several times the total amount of Pu and U obtained from spent fuel. The reported study was funded by RFBR according to the research project № 16-38-00021

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 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.

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.

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

NASA Astrophysics Data System (ADS)

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

2010-12-01

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

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.

CO₂ uptake performance and life cycle assessment of CaO-based sorbents prepared from waste oyster shells blended with PMMA nanosphere scaffolds.

PubMed

Wang, Tsinghai; Xiao, Da-Cheng; Huang, Chih-Hung; Hsieh, Yi-Kong; Tan, Chung-Sung; Wang, Chu-Fang

2014-04-15

In this paper, we demonstrate a means of simultaneously solving two serious environmental issues by reutilization of calcinated mixture of pulverized waste oyster shells blending with poly(methyl methacrylate) (PMMA) nanospheres to prepare CaO-based sorbents for CO2 capture. After 10 cycles of isothermal carbonation/calcination at 750°C, the greatest CO2 uptake (0.19 g CO2/g sorbent) was that for the sorbent featuring 70 wt% of PMMA, which was almost three times higher than that (0.07 g CO2/g sorbent) of untreated waste oyster shell. The greater CO2 uptake was likely a result of particle size reduction and afterwards surface basicity enhancement and an increase in the volume of mesopores and macropores. Following simplified life cycle assessment, whose all input values were collected from our experimental results, suggested that a significant CO2 emission reduction along with lesser human health and ecosystems impacts would be achieved immediately once waste is reutilized. Most importantly, the CO2 uptake efficiency must be greater than 20% or sorbents prepared from limestone mining would eventually produce a net positive CO2 emission. Copyright © 2014 Elsevier B.V. All rights reserved.

Robust and conductive two-dimensional metal-organic frameworks with exceptionally high volumetric and areal capacitance

DOE PAGES

Feng, Dawei; Lei, Ting; Lukatskaya, Maria R.; ...

2018-01-01

For miniaturized capacitive energy storage, volumetric and areal capacitances are more important metrics than gravimetric ones because of the constraints imposed by device volume and chip area. Typically used in commercial supercapacitors, porous carbons, although they provide a stable and reliable performance, lack volumetric performance because of their inherently low density and moderate capacitances. In this paper, we report a high-performing electrode based on conductive hexaaminobenzene (HAB)-derived two-dimensional metal-organic frameworks (MOFs). In addition to possessing a high packing density and hierarchical porous structure, these MOFs also exhibit excellent chemical stability in both acidic and basic aqueous solutions, which is inmore » sharp contrast to conventional MOFs. Submillimetre-thick pellets of HAB MOFs showed high volumetric capacitances up to 760 F cm -3 and high areal capacitances over 20 F cm -2. Furthermore, the HAB MOF electrodes exhibited highly reversible redox behaviours and good cycling stability with a capacitance retention of 90% after 12,000 cycles. In conclusion, these promising results demonstrate the potential of using redox-active conductive MOFs in energy-storage applications.« less

Robust and conductive two-dimensional metal-organic frameworks with exceptionally high volumetric and areal capacitance

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

Feng, Dawei; Lei, Ting; Lukatskaya, Maria R.

For miniaturized capacitive energy storage, volumetric and areal capacitances are more important metrics than gravimetric ones because of the constraints imposed by device volume and chip area. Typically used in commercial supercapacitors, porous carbons, although they provide a stable and reliable performance, lack volumetric performance because of their inherently low density and moderate capacitances. In this paper, we report a high-performing electrode based on conductive hexaaminobenzene (HAB)-derived two-dimensional metal-organic frameworks (MOFs). In addition to possessing a high packing density and hierarchical porous structure, these MOFs also exhibit excellent chemical stability in both acidic and basic aqueous solutions, which is inmore » sharp contrast to conventional MOFs. Submillimetre-thick pellets of HAB MOFs showed high volumetric capacitances up to 760 F cm -3 and high areal capacitances over 20 F cm -2. Furthermore, the HAB MOF electrodes exhibited highly reversible redox behaviours and good cycling stability with a capacitance retention of 90% after 12,000 cycles. In conclusion, these promising results demonstrate the potential of using redox-active conductive MOFs in energy-storage applications.« less

Robust and conductive two-dimensional metal-organic frameworks with exceptionally high volumetric and areal capacitance

NASA Astrophysics Data System (ADS)

Feng, Dawei; Lei, Ting; Lukatskaya, Maria R.; Park, Jihye; Huang, Zhehao; Lee, Minah; Shaw, Leo; Chen, Shucheng; Yakovenko, Andrey A.; Kulkarni, Ambarish; Xiao, Jianping; Fredrickson, Kurt; Tok, Jeffrey B.; Zou, Xiaodong; Cui, Yi; Bao, Zhenan

2018-01-01

For miniaturized capacitive energy storage, volumetric and areal capacitances are more important metrics than gravimetric ones because of the constraints imposed by device volume and chip area. Typically used in commercial supercapacitors, porous carbons, although they provide a stable and reliable performance, lack volumetric performance because of their inherently low density and moderate capacitances. Here we report a high-performing electrode based on conductive hexaaminobenzene (HAB)-derived two-dimensional metal-organic frameworks (MOFs). In addition to possessing a high packing density and hierarchical porous structure, these MOFs also exhibit excellent chemical stability in both acidic and basic aqueous solutions, which is in sharp contrast to conventional MOFs. Submillimetre-thick pellets of HAB MOFs showed high volumetric capacitances up to 760 F cm-3 and high areal capacitances over 20 F cm-2. Furthermore, the HAB MOF electrodes exhibited highly reversible redox behaviours and good cycling stability with a capacitance retention of 90% after 12,000 cycles. These promising results demonstrate the potential of using redox-active conductive MOFs in energy-storage applications.

Nanostructured porous carbons with high rate cycling and floating performance for supercapacitor application

NASA Astrophysics Data System (ADS)

Ochai-Ejeh, F. O.; Momodu, D. Y.; Madito, M. J.; Khaleed, A. A.; Oyedotun, K. O.; Ray, S. C.; Manyala, N.

2018-05-01

Biomass-derived activated carbon from cork (Quercus Suber) (ACQS) was prepared via a two-step environment-friendly route using mild KHCO3 as the activating agent. This synthesis route makes the material produced less toxic for usage as electrode material for energy storage application. The ACQS has well-defined microporous and mesoporous structures and a specific surface area of 1056.52 m2 g-1 and pore volume of 0.64 cm3 g-1. Three-electrode tests were performed in 6 M KOH, 1 M H2SO4 and 3 M KNO3 aqueous electrolytes, to analyse the material performance in acidic, basic, and neutral media. Specific capacitance values (Cs) of 133 F g-1/167 F g-1 at 1.0 A g-1 was obtained in 3 M KNO3 in the positive/negative potential windows. Due to the observed best performance in neutral 3 M KNO3, further electrochemical analysis of the symmetric device was carried out using the same electrolyte. The device displayed a Cs value of 122 F g-1, energy and power densities of ˜14 W h kg-1 and 450 W kg-1 respectively; at 0.5 A g-1. The device also displayed an excellent stability after potentiostatic floating at a maximum voltage of 1.8 V for 120 h and ˜100% capacitance retention after 10,000 charge-discharge cycles. The excellent stability makes the cork-derived material a potential excellent, cost-effective material for supercapacitor application.

On evolutionary climate tracks in deep mantle volatile cycle computed from numerical mantle convection simulations and its impact on the habitability of the Earth-like planets

NASA Astrophysics Data System (ADS)

Nakagawa, T.; Tajika, E.; Kadoya, S.

2017-12-01

Discussing an impact of evolution and dynamics in the Earth's deep interior on the surface climate change for the last few decades (see review by Ehlmann et al., 2016), the mantle volatile (particularly carbon) degassing in the mid-oceanic ridges seems to play a key role in understanding the evolutionary climate track for Earth-like planets (e.g. Kadoya and Tajika, 2015). However, since the mantle degassing occurs not only in the mid-oceanic ridges but also in the wedge mantle (island arc volcanism) and hotspots, to incorporate more accurate estimate of mantle degassing flux into the climate evolution framework, we developed a coupled model of surface climate-deep Earth evolution in numerical mantle convection simulations, including more accurate deep water and carbon cycle (e.g. Nakagawa and Spiegelman, 2017) with an energy balance theory of climate change. Modeling results suggest that the evolution of planetary climate computed from a developed model is basically consistent with an evolutionary climate track in simplified mantle degassing model (Kadoya and Tajika, 2015), but an occurrence timing of global (snowball) glaciation is strongly dependent on mantle degassing rate occurred with activities of surface plate motions. With this implication, the surface plate motion driven by deep mantle dynamics would play an important role in the planetary habitability of such as the Earth and Earth-like planets over geologic time-scale.

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.

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.

Extreme diel dissolved oxygen and carbon cycles in shallow vegetated lakes.

PubMed

Andersen, Mikkel R; Kragh, Theis; Sand-Jensen, Kaj

2017-09-13

A common perception in limnology is that shallow lakes are homogeneously mixed owing to their small water volume. However, this perception is largely gained by downscaling knowledge from large lakes to their smaller counterparts. Here we show that shallow vegetated lakes (less than 0.6 m), in fact, undergo recurring daytime stratification and nocturnal mixing accompanied by extreme chemical variations during summer. Dense submerged vegetation effectively attenuates light and turbulence generating separation between warm surface waters and much colder bottom waters. Photosynthesis in surface waters produces oxygen accumulation and CO 2 depletion, whereas respiration in dark bottom waters causes anoxia and CO 2 accumulation. High daytime pH in surface waters promotes precipitation of CaCO 3 which is re-dissolved in bottom waters. Nocturnal convective mixing re-introduces oxygen into bottom waters for aerobic respiration and regenerated inorganic carbon into surface waters, which supports intense photosynthesis. Our results reconfigure the basic understanding of local environmental gradients in shallow lakes, one of the most abundant freshwater habitats globally. © 2017 The Author(s).

Climatic and ecological impacts of tropospheric sulphate aerosols on the terrestrial carbon cycle

NASA Astrophysics Data System (ADS)

Eliseev, Alexey V.

2015-04-01

Tropospheric sulphate aerosols (TSA) may oxidise the photosynthesising tissues if they are taken up by plants. A parametrisation of this impact of tropospheric sulphate aerosols (TSA) on the terrestrial gross primary production is suggested. This parametrisation is implemented into the global Earth system model developed at the A.M. Obukhov Institute of the Atmospheric Physics, Russian Academy of Sciences (IAP RAS CM). With this coupled model, the simulations are performed which are forced by common anthropogenic and natural climate forcings based on historical reconstructions followed by the RCP 8.5 scenario. The model response to sulphate aerosol loading is subdivided into the climatic (related to the influence of TSA on the radiative transport in the atmosphere) and ecological (related to the toxic influence of sulphate aerosol on terrestrial plants) impacts. We found that the former basically dominates over the latter on the global scale and modifies the responses of the global vegetation and soil carbon stocks to external forcings by 10%. At regional scale, however, ecological impact may be as much important as the climatic one.

Impact of tropospheric sulphate aerosols on the terrestrial carbon cycle

NASA Astrophysics Data System (ADS)

Eliseev, Alexey V.

2015-01-01

Tropospheric sulphate aerosols (TSAs) may oxidise the photosynthesising tissues if they are taken up by plants. A parameterisation of this impact of tropospheric sulphate aerosols (TSAs) on the terrestrial gross primary production is suggested. This parameterisation is implemented into the global Earth system model developed at the A.M. Obukhov Institute of the Atmospheric Physics, Russian Academy of Sciences (IAP RAS CM). With this coupled model, the simulations are performed which are forced by common anthropogenic and natural climate forcings based on historical reconstructions followed by the RCP 8.5 scenario. The model response to sulphate aerosol loading is subdivided into the climatic (related to the influence of TSA on the radiative transport in the atmosphere) and ecological (related to the toxic influence of sulphate aerosol on terrestrial plants) impacts. We found that the former basically dominates over the latter on a global scale and modifies the responses of the global vegetation and soil carbon stocks to external forcings by 10%. At a regional scale, however, ecological impact may be as much important as the climatic one.

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.

Whole Planet Coupling from Climate to Core: Implications for the Evolution of Rocky Planets and their Prospects for Habitability

NASA Astrophysics Data System (ADS)

Foley, B. J.; Driscoll, P. E.

2015-12-01

Many factors have conspired to make Earth a home to complex life. Earth has abundant water due to a combination of factors, including orbital distance and the climate regulating feedbacks of the long-term carbon cycle. Earth has plate tectonics, which is crucial for maintaining long-term carbon cycling and may have been an important energy source for the origin of life in seafloor hydrothermal systems. Earth also has a strong magnetic field that shields the atmosphere from the solar wind and the surface from high-energy particles. Synthesizing recent work on these topics shows that water, a temperate climate, plate tectonics, and a strong magnetic field are linked together through a series of negative feedbacks that stabilize the system over geologic timescales. Although the physical mechanism behind plate tectonics on Earth is still poorly understood, climate is thought to be important. In particular, temperate surface temperatures are likely necessary for plate tectonics because they allow for liquid water that may be capable of significantly lowering lithospheric strength, increase convective stresses in the lithosphere, and enhance the effectiveness of "damage" processes such as grainsize reduction. Likewise, plate tectonics is probably crucial for maintaining a temperate climate on Earth through its role in facilitating the long-term carbon cycle, which regulates atmospheric CO2 levels. Therefore, the coupling between plate tectonics and climate is a feedback that is likely of first order importance for the evolution of rocky planets. Finally, plate tectonics is thought to be important for driving the geodynamo. Plate tectonics efficiently cools the mantle, leading to vigorous thermo-chemical convection in the outer core and dynamo action; without plate tectonics inefficient mantle cooling beneath a stagnant lid may prevent a long-lived magnetic field. As the magnetic field shields a planet's atmosphere from the solar wind, the magnetic field may be important for preserving hydrogen, and therefore water, on the surface. Thus whole planet coupling between the magnetic field, atmosphere, mantle, and core is possible. We lay out the basic physics governing whole planet coupling, and discuss the implications this coupling has for the evolution of rocky planets and their prospects for hosting life.

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.

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.

The fabrication of porous N-doped carbon from widely available urea formaldehyde resin for carbon dioxide adsorption.

PubMed

Liu, Zhen; Du, Zhenyu; Song, Hao; Wang, Chuangye; Subhan, Fazle; Xing, Wei; Yan, Zifeng

2014-02-15

N-doped carbon material constitutes abundant of micropores and basic nitrogen species that have potential implementation for CO2 capture. In this paper, porous carbon material with high nitrogen content was simply fabricated by carbonizing low cost and widely available urea formaldehyde resin, and then followed by KOH activation. CO2 capture experiment showed high adsorption capacity of 3.21 mmol g(-1) at 25 °C under 1 atm for UFCA-2-600. XRD, SEM, XPS and FT-IR analysis confirmed that a graphitic-like structure was retained even after high temperature carbonization and strong base activation. Textural property analysis revealed that narrow micropores, especially below 0.8 nm, were effective for CO2 adsorption by physical adsorption mechanism. Chemical evolved investigation revealed that graphitic-like embedded basic nitrogen groups are generated from bridged and terminal amines of urea formaldehyde resin from thermal carbonization and KOH activation treatment, which is responsible for the enrichment of CO2 capacity by chemical adsorption mechanism. The relationship between CO2 adsorption capacity and pore size or basic N species was also studied, which turned out that both of them played crucial role by physical and chemical adsorption mechanism, respectively. Copyright © 2013 Elsevier Inc. All rights reserved.

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.

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.

The recovery of gold from refractory ores by the use of carbon-in-chlorine leaching

NASA Astrophysics Data System (ADS)

Greaves, John N.; Palmer, Glenn R.; White, William W.

1990-09-01

Recently, the U.S. Bureau of Mines examined the recovery of gold by chlorination of refractory carbonaceous and sulfidic ores, comparing various treatment methods in which a ground ore pulp is contacted with chlorine gas and activated carbon is added to the pulp for a carbon-in-chlorine leach (CICL). The objective of this research was to demonstrate the basic feasibility of CICL technology. Results showed that the organic carbon deactivating environment of CICL lowers, but does not eliminate, the adsorption of gold on activated carbon. In this environment, the refractory ore is altered, and gold is extracted and then recovered on activated carbon. With highly carbonaceous ores, CICL achieved a higher recovery than with primarily sulfidic refractory ores. Basic cyanide amenability testing of two carbonaceous ores achieved recoveries of only 5.5% and 46%. With CICL treatment, recoveries on carbon were 90% and 92%.

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.

Adsorption of basic Red 46 using sea mango (Cerbera odollam) based activated carbon

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

Azmi, Nur Azira Iqlima; Zainudin, Nor Fauziah; Ali, Umi Fazara Md

Sea mango or Cerbera Odollam is another source of carbonaceous material that can be found abundantly in Malaysia. In this research, it is used as a new agricultural source of activated carbon. Sea mango activated carbon was prepared by chemical activation using potassium hydroxide (KOH). The sea mango was soaked in KOH at impregnation ratio of 1:1 and followed by carbonization at temperature of 600°C for 1 hour. The sample was then characterized using Scanning Electron Microscope (SEM) for surface morphology, while Brunauer-Emmett-Teller (BET) was used to study the surface area. The result shown that sea mango activated carbon (SMAC)more » developed new pores on its surface and the BET surface area measured was 451.87 m{sup 2}/g. The SMAC performance was then tested for the removal of Basic Red 46 in batch process. The removal of Basic Red 46 (50 mg/L, natural pH, 0.1 g SMAC) was more than 99% in 15 minutes where it reached equilibrium in 30 minutes.« less

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.

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.

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.

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.

Novel hierarchically porous carbon materials obtained from natural biopolymer as host matrixes for lithium-sulfur battery applications.

PubMed

Zhang, Bin; Xiao, Min; Wang, Shuanjin; Han, Dongmei; Song, Shuqin; Chen, Guohua; Meng, Yuezhong

2014-08-13

Novel hierarchically porous carbon materials with very high surface areas, large pore volumes and high electron conductivities were prepared from silk cocoon by carbonization with KOH activation. The prepared novel porous carbon-encapsulated sulfur composites were fabricated by a simple melting process and used as cathodes for lithium sulfur batteries. Because of the large surface area and hierarchically porous structure of the carbon material, soluble polysulfide intermediates can be trapped within the cathode and the volume expansion can be alleviated effectively. Moreover, the electron transport properties of the carbon materials can provide an electron conductive network and promote the utilization rate of sulfur in cathode. The prepared carbon-sulfur composite exhibited a high specific capacity and excellent cycle stability. The results show a high initial discharge capacity of 1443 mAh g(-1) and retain 804 mAh g(-1) after 80 discharge/charge cycles at a rate of 0.5 C. A Coulombic efficiency retained up to 92% after 80 cycles. The prepared hierarchically porous carbon materials were proven to be an effective host matrix for sulfur encapsulation to improve the sulfur utilization rate and restrain the dissolution of polysulfides into lithium-sulfur battery electrolytes.

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.

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

Dubey, Manvendra; Parket, Harrison; Myers, Katherine

Forests soak up 25% of the carbon dioxide (CO2) emitted by anthropogenic fossil energy use (10 Gt C y-1), moderating its atmospheric accumulation. How this terrestrial CO2 uptake will evolve with climate change in the 21st Century is largely unknown. Rainforests are the most active ecosystems, with the Amazon basin storing 120 Gt C as biomass and exchanging 18 Gt C y-1 of CO2 via photosynthesis and respiration and fixing carbon at 2-3 kg C m-2 y-1. Furthermore, the intense hydrologic and carbon cycles are tightly coupled in the Amazon where about half of the water is recycled by evapotranspirationmore » and the other half imported from the ocean by Northeasterly trade winds. Climate models predict a drying in the Amazon with reduced carbon uptake while observationally guided assessments indicate sustained uptake. We set out to resolve this huge discrepancy in the size and sign of the future Amazon carbon cycle by performing the first simultaneous regional-scale high-frequency measurements of atmospheric CO2, H2O, HOD, CH4, N2O, and CO at the T3 site in Manacupuru, Brazil, as part of DOE's GoAmazon 2014/15 project. Our data will be used to inform and develop DOE's Community Land Model (CLM) on the tropical carbon-water couplings at the appropriate grid scale (10-50 km). Our measurements will also validate the CO2 data from Japan's Greenhouse gases Observing Satellite (GOSAT) and NASA's Orbiting Carbon Observatory (OCO)-2 satellite (launched in July, 2014). Our data addresses these science questions: 1. How does ecosystem heterogeneity and climate variability influence the rainforest carbon cycle? 2. How well do current tropical ecosystem models simulate the observed regional carbon cycle? 3. Does nitrogen deposition (from the Manaus, Brazil, plume) enhance rainforest carbon uptake?« less

Alternative ways of using field-based estimates to calibrate ecosystem models and their implications for ecosystem carbon cycle studies

Treesearch

Y. He; Q. Zhuang; A.D. McGuire; Y. Liu; M. Chen

2013-01-01

Model-data fusion is a process in which field observations are used to constrain model parameters. How observations are used to constrain parameters has a direct impact on the carbon cycle dynamics simulated by ecosystem models. In this study, we present an evaluation of several options for the use of observations inmodeling regional carbon dynamics and explore the...

Life cycle impacts of forest management and wood utilization on carbon mitigation : knowns and unknowns

Treesearch

Bruce Lippke; Elaine Oneil; Rob Harrison; Kenneth Skog; Leif Gustavsson; Roger Sathre

2011-01-01

This review on research on life cycle carbon accounting examines the complexities in accounting for carbon emissions given the many different ways that wood is used. Recent objectives to increase the use of renewable fuels have raised policy questions, with respect to the sustainability of managing our forests as well as the impacts of how best to use wood from our...

Process contributions of Australian ecosystems to interannual variations in the carbon cycle

NASA Astrophysics Data System (ADS)

Haverd, Vanessa; Smith, Benjamin; Trudinger, Cathy

2016-05-01

New evidence is emerging that semi-arid ecosystems dominate interannual variability (IAV) of the global carbon cycle, largely via fluctuating water availability associated with El Niño/Southern Oscillation. Recent evidence from global terrestrial biosphere modelling and satellite-based inversion of atmospheric CO2 point to a large role of Australian ecosystems in global carbon cycle variability, including a large contribution from Australia to the record land sink of 2011. However the specific mechanisms governing this variability, and their bioclimatic distribution within Australia, have not been identified. Here we provide a regional assessment, based on best available observational data, of IAV in the Australian terrestrial carbon cycle and the role of Australia in the record land sink anomaly of 2011. We find that IAV in Australian net carbon uptake is dominated by semi-arid ecosystems in the east of the continent, whereas the 2011 anomaly was more uniformly spread across most of the continent. Further, and in contrast to global modelling results suggesting that IAV in Australian net carbon uptake is amplified by lags between production and decomposition, we find that, at continental scale, annual variations in production are dampened by annual variations in decomposition, with both fluxes responding positively to precipitation anomalies.

Monitoring the Electrochemical Processes in the Lithium–Air Battery by Solid State NMR Spectroscopy

PubMed Central

2013-01-01

A multi-nuclear solid-state NMR approach is employed to investigate the lithium–air battery, to monitor the evolution of the electrochemical products formed during cycling, and to gain insight into processes affecting capacity fading. While lithium peroxide is identified by 17O solid state NMR (ssNMR) as the predominant product in the first discharge in 1,2-dimethoxyethane (DME) based electrolytes, it reacts with the carbon cathode surface to form carbonate during the charging process. 13C ssNMR provides evidence for carbonate formation on the surface of the carbon cathode, the carbonate being removed at high charging voltages in the first cycle, but accumulating in later cycles. Small amounts of lithium hydroxide and formate are also detected in discharged cathodes and while the hydroxide formation is reversible, the formate persists and accumulates in the cathode upon further cycling. The results indicate that the rechargeability of the battery is limited by both the electrolyte and the carbon cathode stability. The utility of ssNMR spectroscopy in directly detecting product formation and decomposition within the battery is demonstrated, a necessary step in the assessment of new electrolytes, catalysts, and cathode materials for the development of a viable lithium–oxygen battery. PMID:24489976

Coating dental implant abutment screws with diamondlike carbon doped with diamond nanoparticles: the effect on maintaining torque after mechanical cycling.

PubMed

Lepesqueur, Laura Soares; de Figueiredo, Viviane Maria Gonçalves; Ferreira, Leandro Lameirão; Sobrinho, Argemiro Soares da Silva; Massi, Marcos; Bottino, Marco Antônio; Nogueira Junior, Lafayette

2015-01-01

To determine the effect of maintaining torque after mechanical cycling of abutment screws that are coated with diamondlike carbon and coated with diamondlike carbon doped with diamond nanoparticles, with external and internal hex connections. Sixty implants were divided into six groups according to the type of connection (external or internal hex) and the type of abutment screw (uncoated, coated with diamondlike carbon, and coated with diamondlike carbon doped with diamond nanoparticles). The implants were inserted into polyurethane resin and crowns of nickel chrome were cemented on the implants. The crowns had a hole for access to the screw. The initial torque and the torque after mechanical cycling were measured. The torque values maintained (in percentages) were evaluated. Statistical analysis was performed using one-way analysis of variance and the Tukey test, with a significance level of 5%. The largest torque value was maintained in uncoated screws with external hex connections, a finding that was statistically significant (P = .0001). No statistically significant differences were seen between the groups with and without coating in maintaining torque for screws with internal hex connections (P = .5476). After mechanical cycling, the diamondlike carbon with and without diamond doping on the abutment screws showed no improvement in maintaining torque in external and internal hex connections.

Carbon-nitrogen-water interactions: is model parsimony fruitful?

NASA Astrophysics Data System (ADS)

Puertes, Cristina; González-Sanchis, María; Lidón, Antonio; Bautista, Inmaculada; Lull, Cristina; Francés, Félix

2017-04-01

It is well known that carbon and nitrogen cycles are highly intertwined and both should be explained through the water balance. In fact, in water-controlled ecosystems nutrient deficit is related to this water scarcity. For this reason, the present study compares the capability of three models in reproducing the interaction between the carbon and nitrogen cycles and the water cycle. The models are BIOME-BGCMuSo, LEACHM and a simple carbon-nitrogen model coupled to the hydrological model TETIS. Biome-BGCMuSo and LEACHM are two widely used models that reproduce the carbon and nitrogen cycles adequately. However, their main limitation is that these models are quite complex and can be too detailed for watershed studies. On the contrary, the TETIS nutrient sub-model is a conceptual model with a vertical tank distribution over the active soil depth, dividing it in two layers. Only the input of the added litter and the losses due to soil respiration, denitrification, leaching and plant uptake are considered as external fluxes. Other fluxes have been neglected. The three models have been implemented in an experimental plot of a semi-arid catchment (La Hunde, East of Spain), mostly covered by holm oak (Quercus ilex). Plant transpiration, soil moisture and runoff have been monitored daily during nearly two years (26/10/2012 to 30/09/2014). For the same period, soil samples were collected every two months and taken to the lab in order to obtain the concentrations of dissolved organic carbon, microbial biomass carbon, ammonium and nitrate. In addition, between field trips soil samples were placed in PVC tubes with resin traps and were left incubating (in situ buried cores). Thus, mineralization and nitrification accumulated fluxes for two months, were obtained. The ammonium and nitrate leaching accumulated for two months were measured using ion-exchange resin cores. Soil respiration was also measured every field trip. Finally, water samples deriving from runoff, were collected to obtain the concentrations of dissolved organic carbon, dissolved organic nitrogen, ammonium and nitrate. The comparison shows a better performance of the complex models reproducing carbon and nitrogen cycles. However, the TETIS nutrient sub-model, even simpler than BIOME-BGCMuSo and LEACHM, reproduces the water balance adequately and it obtains a suitable representation of the carbon and nitrogen cycles.

40 CFR 63.1257 - Test methods and compliance procedures.

Code of Federal Regulations, 2013 CFR

2013-07-01

... the design minimum and average flame zone temperatures and combustion zone residence time; and shall... establish the design exhaust vent stream organic compound concentration level, adsorption cycle time, number... regeneration cycle, design carbon bed temperature after regeneration, design carbon bed regeneration time, and...

40 CFR 63.1257 - Test methods and compliance procedures.

Code of Federal Regulations, 2014 CFR

2014-07-01

... the design minimum and average flame zone temperatures and combustion zone residence time; and shall... establish the design exhaust vent stream organic compound concentration level, adsorption cycle time, number... regeneration cycle, design carbon bed temperature after regeneration, design carbon bed regeneration time, and...

Evidence for microbial carbon and sulfur cycling in deeply buried ridge flank basalt

USGS Publications Warehouse

Lever, Mark A.; Rouxel, Olivier; Alt, Jeffrey C.; Shimizu, Nobumichi; Ono, Shuhei; Coggon, Rosalind M.; Shanks, Wayne C.; Lapham, Laura; Elvert, Marcus; Prieto-Mollar, Xavier; Hinrichs, Kai-Uwe; Inagaki, Fumio; Teske, Andreas

2013-01-01

Sediment-covered basalt on the flanks of mid-ocean ridges constitutes most of Earth's oceanic crust, but the composition and metabolic function of its microbial ecosystem are largely unknown. By drilling into 3.5-million-year-old subseafloor basalt, we demonstrated the presence of methane- and sulfur-cycling microbes on the eastern flank of the Juan de Fuca Ridge. Depth horizons with functional genes indicative of methane-cycling and sulfate-reducing microorganisms are enriched in solid-phase sulfur and total organic carbon, host δ13C- and δ34S-isotopic values with a biological imprint, and show clear signs of microbial activity when incubated in the laboratory. Downcore changes in carbon and sulfur cycling show discrete geochemical intervals with chemoautotrophic δ13C signatures locally attenuated by heterotrophic metabolism.

The adsorption of NO, NH3, N2 on carbon surface: a density functional theory study.

PubMed

Wang, Jiayong; Yang, Mo; Deng, Debing; Qiu, Shuxia

2017-08-11

To explore the adsorption mechanism of NO, NH 3 , N 2 on a carbon surface, and the effect of basic and acidic functional groups, density functional theory was employed to investigate the interactions between these molecules and carbon surfaces. Molecular electrostatic potential, Mulliken population analyses, reduced density gradient, and Mayer bond order analyses were used to clarify the adsorption mechanism. The results indicate that van der Waals interactions are responsible for N 2 physisorption, and N 2 is the least likely to adsorb on a carbon surface. Modification of carbon materials to decorate basic or acidic functional groups could enhance the NH 3 physisorption because of hydrogen bonding or electrostatic interactions, however, NO physisorption on a carbon surface is poor. Zig-zag sites are more reactive than armchair sites when these gas molecules absorb on the edge sites of carbon surface. Graphical abstract NH 3 , N 2 , NO adsortion on carbon surface.

A climate sensitive model of carbon transfer through atmosphere, vegetation and soil in managed forest ecosystems

NASA Astrophysics Data System (ADS)

Loustau, D.; Moreaux, V.; Bosc, A.; Trichet, P.; Kumari, J.; Rabemanantsoa, T.; Balesdent, J.; Jolivet, C.; Medlyn, B. E.; Cavaignac, S.; Nguyen-The, N.

2012-12-01

For predicting the future of the forest carbon cycle in forest ecosystems, it is necessary to account for both the climate and management impacts. Climate effects are significant not only at a short time scale but also at the temporal horizon of a forest life cycle e.g. through shift in atmospheric CO2 concentration, temperature and precipitation regimes induced by the enhanced greenhouse effect. Intensification of forest management concerns an increasing fraction of temperate and tropical forests and untouched forests represents only one third of the present forest area. Predicting tools are therefore needed to project climate and management impacts over the forest life cycle and understand the consequence of management on the forest ecosystem carbon cycle. This communication summarizes the structure, main components and properties of a carbon transfer model that describes the processes controlling the carbon cycle of managed forest ecosystems. The model, GO+, links three main components, (i) a module describing the vegetation-atmosphere mass and energy exchanges in 3D, (ii) a plant growth module and a (iii) soil carbon dynamics module in a consistent carbon scheme of transfer from atmosphere back into the atmosphere. It was calibrated and evaluated using observed data collected on coniferous and broadleaved forest stands. The model predicts the soil, water and energy balance of entire rotations of managed stands from the plantation to the final cut and according to a range of management alternatives. It accounts for the main soil and vegetation management operations such as soil preparation, understorey removal, thinnings and clearcutting. Including the available knowledge on the climatic sensitivity of biophysical and biogeochemical processes involved in atmospheric exchanges and carbon cycle of forest ecosystems, GO+ can produce long-term backward or forward simulations of forest carbon and water cycles under a range of climate and management scenarios. This model applications to the prediction and analysis of climate scenarios impacts on southwestern European forests underlines the role of management alternatives, precipitation regime, CO2 concentration and atmospheric humidity .Frequency of soil preparation operations and understorey management play a major role in controlling the net carbon flux into the atmosphere at the juvenile stage ( 0 to 10 y-old) whereas climate and rotation duration control the functioning of adult phase. The model predicts that a drier and warmer climate will reduce the forest productivity and deplete soil and carbon stocks in managed forest from Southwestern Europe within decades, such effects being amplified for most intensive management alternatives. This work was part of the European research project GHG-Europe (EU contract No. 244122) and the French national project FAST co-funded by the Ecology, Agriculture and Forestry Ministries and the Region Aquitaine.

Impacts of disturbance history on annual carbon stocks and fluxes in southeastern US forests during 1986-2010 using remote sensing, forest inventory data, and a carbon cycle model

NASA Astrophysics Data System (ADS)

Gu, H.; Zhou, Y.; Williams, C. A.

2017-12-01

Accurate assessment of forest carbon storage and uptake is central to policymaking aimed at mitigating climate change and understanding the role forests play in the global carbon cycle. Disturbance events are highly heterogeneous in space and time, impacting forest carbon dynamics and challenging the quantification and reporting of carbon stocks and fluxes. This study documents annual carbon stocks and fluxes from 1986 and 2010 mapped at 30-m resolution across southeastern US forests, characterizing how they respond to disturbances and ensuing regrowth. Forest inventory data (FIA) are used to parameterize a carbon cycle model (CASA) to represent post-disturbance carbon trajectories of carbon pools and fluxes with time following harvest, fire and bark beetle disturbances of varying severity and across forest types and site productivity settings. Time since disturbance at 30 meters is inferred from two remote-sensing data sources: disturbance year (NAFD, MTBS and ADS) and biomass (NBCD 2000) intersected with FIA-derived curves of biomass accumulation with stand age. All of these elements are combined to map carbon stocks and fluxes at a 30-m resolution for the year 2010, and to march backward in time for continuous, annual reporting. Results include maps of annual carbon stocks and fluxes for forests of the southeastern US, and analysis of spatio-temporal patterns of carbon sources/sinks at local and regional scales.

Implications of a More Comprehensive Nitrogen Cycle in a Global Biogeochemical Ocean Model

NASA Astrophysics Data System (ADS)

Six, K. D.; Ilyina, T.

2016-02-01

Nitrogen plays a crucial role for nearly all living organisms in the Earth system. Changes in the marine nitrogen cycle not only alter the marine biota, but will also have an impact on the marine carbon cycle and, in turn, on climate due to the close coupling of the carbon-nitrogen cycle. The understanding of processes and controls of the marine nitrogen cycle is therefore a prerequisite to reduce uncertainties in the prediction of future climate. Nevertheless, most ocean biogeochemical components of modern Earth system models have a rather simplistic representation of marine N-cycle mainly focusing on nitrate. Here we present results of the HAMburg Ocean Carbon Cycle model (HAMOCC) as part of the MPI-ESM which was extended by a prognostic representation of ammonium and nitrite to resolve important processes of the marine N-cycle such as nitrification and anaerobic ammonium oxidation (anammox). Additionally, we updated the production of nitrous oxide, an important greenhouse gas, allowing for two sources from oxidation of ammonium (nitrification) and from reduction of nitrite (nitrifier-denitrification) at low oxygen concentrations. Besides an extended model data comparison we discuss the following aspects of the N-cycle by model means: (1) contribution of anammox to the loss of fixed nitrogen, and (2) production and emission of marine nitrous oxide.

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

NONE

Exploration of various types of power plant cycles for nuclear propelled aircraft has been continued during this quarter. The principal current objective of the project is the development of information which will make an intelligent choice of the basic power plant cycle possible. It is still hoped that this choice can be made late in 1950. The survey studies which have been under way for several months continued during the quarter. These consist of analyses and rough preliminary layouts for various types of aircraft, using each of the several basic cycles which have been seriously considered for each of themore » three phases of development. Although it is still extremely premature to discuss the relative merits of the various cycles, the information so for developed discloses some cycle differences which may, if confirmed by additional work, be significant. In this respect, there have been no recent major changes in the comparative standings of the cycles.« less

Advanced electric propulsion system concept for electric vehicles

NASA Technical Reports Server (NTRS)

Raynard, A. E.; Forbes, F. E.

1979-01-01

Seventeen propulsion system concepts for electric vehicles were compared to determine the differences in components and battery pack to achieve the basic performance level. Design tradeoffs were made for selected configurations to find the optimum component characteristics required to meet all performance goals. The anticipated performance when using nickel-zinc batteries rather than the standard lead-acid batteries was also evaluated. The two systems selected for the final conceptual design studies included a system with a flywheel energy storage unit and a basic system that did not have a flywheel. The flywheel system meets the range requirement with either lead-acid or nickel-zinc batteries and also the acceleration of zero to 89 km/hr in 15 s. The basic system can also meet the required performance with a fully charged battery, but, when the battery approaches 20 to 30 percent depth of discharge, maximum acceleration capability gradually degrades. The flywheel system has an estimated life-cycle cost of $0.041/km using lead-acid batteries. The basic system has a life-cycle cost of $0.06/km. The basic system, using batteries meeting ISOA goals, would have a life-cycle cost of $0.043/km.

Carbon cycling in terrestrial environments: Chapter 17

USGS Publications Warehouse

Wang, Yang; Huntington, Thomas G.; Osher, Laurie J.; Wassenaar, Leonard I; Trumbore, Susan E.; Amundson, Ronald; Harden, Jennifer W.; McKnight, Diane M.; Schiff, Sherry L.; Aiken, George R.; Lyons, W. Berry; Aravena, Ramon O.; Baron, Jill S.

1998-01-01

This chapter reviews a number of applications of isotopic techniques for the investigation of carbon cycling processes. Carbon dioxide (C02) is an important greenhouse gas. Its concentration in the atmosphere has increased from an estimated 270 ppm at the beginning of the industrial revolution to ∼ 360 ppm at present. Climatic conditions and atmospheric C02 concentration also influence isotopic discrimination during photosynthesis. Natural and anthropogenically induced variations in the carbon isotopic abundance can be exploited to investigate carbon transformations between pools on various time scales. It also discusses one of the isotopes of carbon, the 14C, that is produced in the atmosphere by interactions of cosmic-ray produced neutrons with stable isotopes of nitrogen (N), oxygen (O), and carbon (C), and has a natural abundance in the atmosphere of ∼1 atom 14 C per 1012 atoms 12C. The most important factor affecting the measured 14C ages of soil organic matter is the rate of organic carbon cycling in soils. Differences in the dynamics of soil carbon among different soils or soil horizons will result in different soil organic 14C signatures. As a result, the deviation of the measured 14C age from the true age could differ significantly among different soils or soil horizons.

The carbon cycle and associated redox processes through time

PubMed Central

Hayes, John M; Waldbauer, Jacob R

2006-01-01

Earth's biogeochemical cycle of carbon delivers both limestones and organic materials to the crust. In numerous, biologically catalysed redox reactions, hydrogen, sulphur, iron, and oxygen serve prominently as electron donors and acceptors. The progress of these reactions can be reconstructed from records of variations in the abundance of 13C in sedimentary carbonate minerals and organic materials. Because the crust is always receiving new CO2 from the mantle and a portion of it is being reduced by photoautotrophs, the carbon cycle has continuously released oxidizing power. Most of it is represented by Fe3+ that has accumulated in the crust or been returned to the mantle via subduction. Less than 3% of the estimated, integrated production of oxidizing power since 3.8 Gyr ago is represented by O2 in the atmosphere and dissolved in seawater. The balance is represented by sulphate. The accumulation of oxidizing power can be estimated from budgets summarizing inputs of mantle carbon and rates of organic-carbon burial, but levels of O2 are only weakly and indirectly coupled to those phenomena and thus to carbon-isotopic records. Elevated abundances of 13C in carbonate minerals ca 2.3 Gyr old, in particular, are here interpreted as indicating the importance of methanogenic bacteria in sediments rather than increased burial of organic carbon. PMID:16754608

From position-specific isotope labeling towards soil fluxomics: a novel toolbox to assess the microbial impact on biogeochemical cycles

NASA Astrophysics Data System (ADS)

Apostel, C.; Dippold, M. A.; Kuzyakov, Y.

2015-12-01

Understanding the microbial impact on C and nutrient cycles is one of the most important challenges in terrestrial biogeochemistry. Transformation of low molecular weight organic substances (LMWOS) is a key step in all biogeochemical cycles because 1) all high molecular substances pass the LMWOS pool during their degradation and 2) only LMWOS can be taken up by microorganisms intact. Thus, the transformations of LMWOS are dominated by biochemical pathways of the soil microorganisms. Thus, understanding fluxes and transformations in soils requires a detailed knowledge on the microbial metabolic network and its control mechanism. Tracing C fate in soil by isotopes became on of the most applied and promising biogeochemistry tools but studies were nearly exclusively based on uniformly labeled substances. However, such tracers do not allow the differentiation of the intact use of the initial substances from its transformation to metabolites. The novel tool of position-specific labeling enables to trace molecule atoms separately and thus to determine the cleavage of molecules - a prerequisite for metabolic tracing. Position-specific labeling of basic metabolites and quantification of isotope incorporation in CO2 and bulk soil enabled following the basic metabolic pathways of microorganisms. However, the combination of position-specific 13C labeling with compound-specific isotope analysis of microbial biomarkers and metabolites like phospholipid fatty acids (PLFA) or amino sugars revealed new insights into the soil fluxome: First, it enables tracing specific anabolic pathways in diverse microbial communities in soils e.g. carbon starvation pathways versus pathways reflecting microbial growth. Second, it allows identification of specific pathways of individual functional microbial groups in soils in situ. Tracing metabolic pathways and understanding their regulating factors are crucial for soil C fluxomics i.e. the unravaling of the complex network of C transformations. Quantitative models to assess microbial group specific metabolic pathways can be generated and parameterized by this approach. The knowledge of submolecular C transformation steps and its regulating factors is essential for understanding C cycling and long-term C storage in soils.

SOLAR ULTRAVIOLET RADIATION AND AQUATIC CARBON, NITROGEN, SULFUR AND METALS CYCLES

EPA Science Inventory

Solar ultraviolet radiation (290-400 nm) has a wide-ranging impact on biological and chemical processes that affect the cycling of elements in aquatic environments. This chapter uses recent field and laboratory observations along with models to assess these impacts on carbon, nit...

40 CFR Table 20 to Subpart G of... - Wastewater-Periodic Reporting Requirements for Control Devices Subject to § 63.139 Used To Comply...

Code of Federal Regulations, 2014 CFR

2014-07-01

... (Regenerative) (i) Report all carbon bed regeneration cycles when the total regeneration stream mass or... regeneration cycles during which the temperature of the carbon bed after regeneration is outside the range...

40 CFR Table 20 to Subpart G of... - Wastewater-Periodic Reporting Requirements for Control Devices Subject to § 63.139 Used To Comply...

Code of Federal Regulations, 2012 CFR

2012-07-01

... (Regenerative) (i) Report all carbon bed regeneration cycles when the total regeneration stream mass or... regeneration cycles during which the temperature of the carbon bed after regeneration is outside the range...

40 CFR Table 20 to Subpart G of... - Wastewater-Periodic Reporting Requirements for Control Devices Subject to § 63.139 Used To Comply...

Code of Federal Regulations, 2010 CFR

2010-07-01

... (Regenerative) (i) Report all carbon bed regeneration cycles when the total regeneration stream mass or... regeneration cycles during which the temperature of the carbon bed after regeneration is outside the range...

40 CFR Table 20 to Subpart G of... - Wastewater-Periodic Reporting Requirements for Control Devices Subject to § 63.139 Used To Comply...

Code of Federal Regulations, 2013 CFR

2013-07-01

... (Regenerative) (i) Report all carbon bed regeneration cycles when the total regeneration stream mass or... regeneration cycles during which the temperature of the carbon bed after regeneration is outside the range...