نتایج جستجو برای: atmospheric carbon

تعداد نتایج: 348398  

2006
Nathan D. Sheldon

Precambrian atmospheric pCO2 levels were previously estimated using a simple thermodynamic model based on the mineral assemblage in paleosols. In addition to theoretical flaws with that model, recalculation of pCO2 levels using more recent thermodynamic data gives significantly lower values. A new model based on the mass balance of weathering in paleosols gives consistent results from three sep...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه تربیت دبیر شهید رجایی - دانشکده علوم پایه 1391

این پژوهش به اکسید اسیون متانول در محیط قلیایی می پردازد. برای این منظور ابتدا ترسیب ذرات نیکل، پلاتین و نیکل – پلاتین بر روی زیر لایه کاغذ کربنی به روش آبکاری به شیوه ی جریان مستقیم استفاده شد. در ادامه مورفولوژی پوشش های ذرات فلزی بر روی کاغذ کربنی از طریق میکروسکوپ الکترونی روبشی بررسی و مطالعه شد. سپس خواص کاتالیستی الکترودها ی حاصل در اکسیداسیون متانول با استفاده از روشهای الکتروشیمیایی هم...

2011
Gregory S. Okin Alex R. Baker Ina Tegen Natalie M. Mahowald Frank J. Dentener Robert A. Duce James N. Galloway Keith Hunter Maria Kanakidou Nilgun Kubilay Joseph M. Prospero Manmohan Sarin Vanisa Surapipith Mitsuo Uematsu Tong Zhu

[1] Nutrients are supplied to the mixed layer of the open ocean by either atmospheric deposition or mixing from deeper waters, and these nutrients drive nitrogen and carbon fixation. To evaluate the importance of atmospheric deposition, we estimate marine nitrogen and carbon fixation from present‐day simulations of atmospheric deposition of nitrogen, phosphorus, and iron. These are compared wit...

Journal: :جنگل و فرآورده های چوب 0
ضیاءالدین باده یان استادیار دانشگاه لرستان معصومه منصوری دانشجوی دکترا دانشگاه لرستان محبوبه فسحت دانشجوی کارشناسی ارشد دانشگاه تربیت مدرس محمد علی فخاری کارشناس ارشد سازمان جنگلها، مراتع و آبخیزداری کشور. سید محسن حسینی دانشیار دانشکده منابع طبیعی و علوم دریایی دانشگاه تربیت مدرس، پردیس نور

forest ecosystems and their optimal management can play effective roles in mitigating the carbon emission as well as absorbing the atmospheric carbon. the present research was carried out to determine the effects of 21 year old stands of cryptomeria japonica, cupressus sempervirens, pinus taeda, acer pseudo-platanu and mixed plantation and natural forest stands on sequestration of carbon in the...

Journal: :Science 2005
James Heath Edward Ayres Malcolm Possell Richard D Bardgett Helaina I J Black Helen Grant Phil Ineson Gerhard Kerstiens

Forests have a key role as carbon sinks, which could potentially mitigate the continuing increase in atmospheric carbon dioxide concentration and associated climate change. We show that carbon dioxide enrichment, although causing short-term growth stimulation in a range of European tree species, also leads to an increase in soil microbial respiration and a marked decline in sequestration of roo...

2005
S. S. Assonov C. A. M. Brenninkmeijer P. Jöckel R. Mulvaney

A reconstruction of the past trend of atmospheric CO based on firn air samples from Berkner Island, Antarctica S. S. Assonov, C. A. M. Brenninkmeijer, P. Jöckel, R. Mulvaney, and S. Bernard Max Planck Institute for Chemistry, Atmospheric Chemistry Department, P.O. Box 3060, 55020 Mainz, Germany British Antarctic Survey, High Cross, Madingley Road, Cambridge CB3 0ET, UK Laboratoire de Glaciologi...

2007
J. C. Doran J. D. Fast J. C. Barnard A. Laskin Y. Desyaterik M. K. Gilles

Applications of Lagrangian dispersion modeling to the analysis of changes in the specific absorption of elemental carbon J. C. Doran, J. D. Fast, J. C. Barnard, A. Laskin, Y. Desyaterik, M. K. Gilles, and R. J. Hopkins Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington, USA Lawrence Berkeley National Laboratory, Berkeley, CA, USA Received: 25 September 2007 – Accepted: 10...

Journal: :آب و خاک 0
حلاج نیا حلاج نیا حق نیا حق نیا لکزیان لکزیان رمضانیان رمضانیان

elevated atmospheric carbon dioxide and other green house gases have increased the earth temperature in recent century, which it affects all biochemistry cycles in soils. to examine the effect of atmospheric co2 concentration and temperature on n forms in soil solution in a calcareous soil, an experiment was conducted in a completely randomized design with factorial arrangement in the laborator...

2009
A. Tagliabue L. Bopp D. M. Roche

We use a state-of-the-art ocean general circulation and biogeochemistry model to examine the impact of changes in ocean circulation and biogeochemistry in governing the change in ocean carbon-13 and atmospheric CO2 at the last glacial maximum (LGM). We examine 5 different realisations of the ocean’s overturning circulation produced by a fully coupled atmosphere-ocean model under LGM forcing and...

2000
JJ DOOLEY JA EDMONDS

In this paper, we examine the potential of carbon capture and sequestration technologies to make a significant contribution to national and global efforts to control carbon dioxide (CO2) emissions. We examine the performance of these technologies under two alternative future energy-policy scenarios. We conclude that carbon capture and sequestration technologies could indeed play a significant r...

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