نتایج جستجو برای: chemical weathering

تعداد نتایج: 382710  

2011
E. Beaulieu

This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the co...

Journal: :Proceedings of the National Academy of Sciences of the United States of America 2017
Mark A Torres Nils Moosdorf Jens Hartmann Jess F Adkins A Joshua West

Connections between glaciation, chemical weathering, and the global carbon cycle could steer the evolution of global climate over geologic time, but even the directionality of feedbacks in this system remain to be resolved. Here, we assemble a compilation of hydrochemical data from glacierized catchments, use this data to evaluate the dominant chemical reactions associated with glacial weatheri...

2008
Pak Kin Wong Fuqu Yu Arash Shahangian Genhong Cheng Ren Sun Ming Ho

Continental crust rises higher than oceanic crust because it is less dense: It is rich in Si and poor in Mg. However, basalt, which is derived from magma, is denser and has a higher ratio of Mg to Si than the rock that makes up mature continental crust. Cin-Ty Lee et al. argue that chemical weathering alters the composition of continental crust as it ages and helps give it its more buoyant char...

2015
Jingheng Guo Fushun Wang Rolf David Vogt Yuhang Zhang Cong-Qiang Liu

Chemical weathering is a fundamental geochemical process regulating the atmosphere-land-ocean fluxes and earth's climate. It is under natural conditions driven primarily by weak carbonic acid that originates from atmosphere CO2 or soil respiration. Chemical weathering is therefore assumed as positively coupled with its CO2 consumption in contemporary geochemistry. Strong acids (i.e. sulfuric- a...

2006
P. Louvat C. J. Allegre

As chemical weathering of silicate rocks acts as a sink for atmospheric CO2 and as greenhouse effect gases such as CO2 have a leading role in climate regulation, much of river geochemical studies now focus on chemical and mechanical riverine erosion and on their controlling parameters. Moreover, weathering has probably had a dominating influence in the climatic evolution of the Earth, and studi...

2017
Clément P Bataille Amy Willis Xiao Yang Xiao-Ming Liu

The composition of igneous rocks in the continental crust has changed throughout Earth's history. However, the impact of these compositional variations on chemical weathering, and by extension on seawater and atmosphere evolution, is largely unknown. We use the strontium isotope ratio in seawater [(87Sr/86Sr)seawater] as a proxy for chemical weathering, and we test the sensitivity of (87Sr/86Sr...

2017
Gregory M. Olson Heng Gao Buffy M. Meyer M. Scott Miles Edward B. Overton

During the 2010 Deepwater Horizon oil well blowout in the Northern Gulf of Mexico (GoM), the application of 6.97 million litres of chemical dispersants was used at the well-head and on the sea surface to promote oil degradation and weathering of the Mississippi Canyon 252 (MC252) crude oil. Chemical dispersants encourage microbial degradation by increasing the surface area of the spilled oil, w...

2007
Kyungsoo Yoo Ronald Amundson Arjun M. Heimsath William E. Dietrich George H. Brimhall

[1] We developed a process-oriented hillslope soil mass balance model that integrates chemical and physical processes within hillslope soils. The model explicitly factors that soil chemical weathering at any hillslope position is related to the flux of soil eroded from upslope as well as soil production from underlying bedrock. The model was merged with measurements of soil elemental chemistry ...

2008
Zsuzsanna Balogh-Brunstad C. Kent Keller Bernard T. Bormann Rachel O’Brien Deane Wang Gary Hawley

[1] Mineral weathering and chemical denudation of terrestrial environments are understood by both geochemists and ecologists to be affected by rooted plant growth. We used unique 20-year ‘‘sandbox’’ experiments to test the predictions of both disciplines regarding the influence of tree growth and harvest on chemical weathering and denudation of Ca, Mg and K. Results showed 3 temporal phases: 1)...

Journal: :Proceedings of the National Academy of Sciences of the United States of America 2008
Cin-Ty Aeolus Lee Douglas M Morton Mark G Little Ronald Kistler Ulyana N Horodyskyj William P Leeman Arnaud Agranier

Continents ride high above the ocean floor because they are underlain by thick, low-density, Si-rich, and Mg-poor crust. However, the parental magmas of continents were basaltic, which means they must have lost Mg relative to Si during their maturation into continents. Igneous differentiation followed by lower crustal delamination and chemical weathering followed by subduction recycling are pos...

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