910 resultados para Greenhouse gas fluxes


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Stimulus encouraging the production and consumption of biodiesel favors the policy of pre-serving the environment, contributing to the reduction of greenhouse gas reducing climate change. The current trend of research in this field focuses on improving these processes with the use of heterogeneous catalysts, seeing has significant advantages such as: low contamination of products, ease of separation of the catalyst from the reaction medium, possibili-ty of reuse of the catalyst, decreased corrosion problems. The objective of this research was to optimize the synthesis of AlSBA-15 for the production of biodiesel through transesterification process via ethyl route. For the optimization of hydrothermal synthesis of type AlSBA-15 catalyst has assembled a 23 factorial experimental matrix with eleven trials. The stoichiometric amounts of starting materials were varied according to different ratios Si / Al which is a factor in the experimental design, in addition to the time and temperature of aging of the synthesis gel. The material showed the best results of characterization (SBET = 591.7 (m2 / g), Vp = 0.83 (cm3 / g), Dp = 5.59 (nm), w = 6.48 (nm) was synthesized at 100 ° C for 24 hours, with a ratio Si / Al = 10.This material was applied as a heterogeneous catalyst in the reaction of ethyl transesterification as raw coconut oil in natura. Coconut oil presented suitable for obtaining biodiesel via ethyl route.The visual aspects and physical-chemical characteristics of the reaction products show that AlSBA-15 catalyst favored the reaction. According to physical-chemical analysis the order of oxidative stability of the product of the transesterification reaction was: catalytic reaction at 1500 ° C> non-catalytic reaction at 100 ° C> 100 ° C catalytic> catalytic reaction at 200 ° C Reaction. The results of oxidative stability and kinematic viscosity shows that the biodiesel produced in the catalytic sandblasting held at 150 ° C which was maintained within the ABNT NBR 7148, ABNT NBR 10441 and EN 14112.

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The response of natural CH4 sources to climate changes will be an important factor to consider as concentrations of this potent greenhouse gas continue to increase. Polar ice cores provide the means to assess this sensitivity in the past and have shown a close connection between CH4 levels and northern hemisphere temperature variability over the last glacial cycle. However, the contribution of the various CH4 sources and sinks to these changes is still a matter of debate. Contemporaneous stable CH4 isotope records in ice cores provide additional boundary conditions for assessing changes in the CH4 sources and sinks. Here we present new ice core CH4 isotope data covering the last 160,000 years, showing a clear decoupling between CH4 loading and carbon isotopic variations over most of the record. We suggest that d13CH4 variations were not dominated by a change in the source mix but rather by climate- and CO2-related ecosystem control on the isotopic composition of the methane precursor material, especially in seasonally inundated wetlands in the tropics. In contrast, relatively stable d13CH4 intervals occurred during large CH4 loading changes concurrently with past climate changes implying that most CH4 sources (most notably tropical wetlands) responded simultaneously.

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The transport of people and goods contributes to the deterioration of the environment in urban areas because of the generation of pollution, such as, air, noise, soil, water or visual degradation. The heavy vehicles that use diesel as fuel are mainly responsible for the emission of nitrogen oxides (NOx) and particulate matter (PM), contributing to participation of the transport sector in air pollution. In addition, there is emission of Greenhouse Gas (GHG) whose main component is carbon dioxide (CO2). In most major cities, public transportation is often considered as a less polluting alternative compared to the private vehicle, in view of the potential to reduce, per passenger, the emissions of GHG and air pollutants. The study area was the city of Uberlândia and the objects of study were the trunk lines of the Sistema Integrado de Transporte (SIT). The emissions of NOx, PM and CO2 were estimated through the bottom-up approach which used the route of each bus line and also fuel consumption obtained through simulation from the TSIS software. The software has some result limitations, there are no report about the emission of pollutants by bus, and it is not able to change specifications for the fuel used by the fleet. The results obtained through calculations of pollutants and GHG emission by the bottom-up approach show that the emission is higher when using fuel comsuption obtained in simulation than using distance. For the results considering fuel and distance there was a reduction in emissions comparing ethanol and diesel.

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Date of Acceptance: 08/05/2014 Acknowledgements The authors are indebted to Julia Römer for assisting with editing several hundred references. Helmut Haberl gratefully acknowledges funding by the Austrian Academy of Sciences (Global Change Programme), the Austrian Ministry of Science and Research (BMWF, proVision programme) as well as by the EU-FP7 project VOLANTE. Carmenza Robledo-Abad received financial support from the Swiss State Secretariat for Economic Affairs.

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The views expressed herein are those of the authors, and do not represent those of a particular governmental agency or interagency body. This analysis was initiated at a Global Carbon Project meeting on NETs in Laxenburg, Austria, in April 2013 and contributes to the MaGNET program (http://www.cger.nies.go.jp/gcp/magnet.html). G.P.P. was supported by the Norwegian Research Council (236296). C.D.J. was supported by the Joint UK DECC/Defra Met Office Hadley Centre Climate Programme (GA01101). J.G.C. acknowledges support from the Australian Climate Change Science Program. E.Ka. and Y.Y. were supported by the ERTDF (S-10) from the Ministry of the Environment, Japan.

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Acknowledgements This work was supported by NSFC (41371298 and 41371300), Ministry of Science and Technology (2013GB23600666 and 2013BAD11B00), and Ministry of Education of China (20120097130003). The international cooperation was funded under a “111” project by the State Agency of Foreign Expert Affairs of China and jointly supported under a grant for Priority Disciplines in Higher Education by the Department of Education, Jiangsu Province, China; The work was also a contribution to the cooperation project of “Estimates of Future Agricultural GHG Emissions and Mitigation in China” under the UK-China Sustainable Agriculture Innovation Network (SAIN). Pete Smith contributed to this work under a UK BBSRC China Partnership Award.

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Acknowledgements We are grateful to Stefan Seibert for advice on reconciling the Monfreda datasets of yield and area and the Portmann dataset for irrigated area of rice. We thank Deepak Ray and Jonathan Foley for helpful comments. Research support to J.G. K.C., N.M, and P.W. was primarily provided by the Gordon and Betty Moore Foundation and the Institute on Environment, with additional support from NSF Hydrologic Sciences grant 1521210 for N.M., and additional support to J.G. and P.W. whose efforts contribute to Belmont Forum/FACCE-JPI funded DEVIL project (NE/M021327/1). M.H. was supported by CSIRO's OCE Science Leaders Programme and the Agriculture Flagship. Funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

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We would like to thank EPSRC for a Doctoral Training Grant (G.A.M) and the Erasmus programme for supporting the study visit to Turin (R.W). We would also like to thank Dr. Federico Cesano for SEM/EDX measurements and for fruitful discussion. Dr. Jo Duncan is thanked for his tremendous insight during XRD interpretation.

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Date of Acceptance: 08/05/2014 Acknowledgements The authors are indebted to Julia Römer for assisting with editing several hundred references. Helmut Haberl gratefully acknowledges funding by the Austrian Academy of Sciences (Global Change Programme), the Austrian Ministry of Science and Research (BMWF, proVision programme) as well as by the EU-FP7 project VOLANTE. Carmenza Robledo-Abad received financial support from the Swiss State Secretariat for Economic Affairs.