نتایج جستجو برای: mechanical weathering

تعداد نتایج: 242214  

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...

2017
Nick F Pidgeon Elspeth Spence

This paper addresses the social acceptability of enhanced weathering, a technology that would involve spreading silicate particles over terrestrial surfaces in order to boost the biological processes that currently sequester CO2 as part of the earth's natural carbon cycle. We present the first exploration of British attitudes towards enhanced weathering, using an online survey (n = 935) of a re...

Journal: :Philosophical transactions of the Royal Society of London. Series B, Biological sciences 2012
Lyla L Taylor Steve A Banwart Paul J Valdes Jonathan R Leake David J Beerling

Global weathering of calcium and magnesium silicate rocks provides the long-term sink for atmospheric carbon dioxide (CO(2)) on a timescale of millions of years by causing precipitation of calcium carbonates on the seafloor. Catchment-scale field studies consistently indicate that vegetation increases silicate rock weathering, but incorporating the effects of trees and fungal symbionts into geo...

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...

2008
Wei Luo Alan D. Howard

6 [1] The role of groundwater in forming Martian valley networks is simulated in a 7 computer model as seepage erosion by contributing to surface runoff and as seepage 8 weathering by causing accelerated weathering of bedrock, which makes its subsequent 9 erosion and removal easier. Simulation results show that seepage erosion cannot mobilize 10 large grain size sediment and is marginally effec...

2008
Wei Luo Alan D. Howard

[1] The role of groundwater in forming Martian valley networks is simulated in a computer model as seepage erosion by contributing to surface runoff and as seepage weathering by causing accelerated weathering of bedrock, which makes its subsequent erosion and removal easier. Simulation results show that seepage erosion cannot mobilize large grain size sediment and is marginally effective at gen...

2017
Joshua Krissansen-Totton David C. Catling

The relative influences of tectonics, continental weathering and seafloor weathering in controlling the geological carbon cycle are unknown. Here we develop a new carbon cycle model that explicitly captures the kinetics of seafloor weathering to investigate carbon fluxes and the evolution of atmospheric CO2 and ocean pH since 100 Myr ago. We compare model outputs to proxy data, and rigorously c...

2012
Francesca Lionetto Roberta Del Sole Donato Cannoletta Giuseppe Vasapollo Alfonso Maffezzoli

The degree of crystallinity of cellulose was used for assessing the degradation level of coated and uncoated samples of pine wood after weathering. X-ray diffraction (XRD) and Fourier Transform Infrared (FT-IR) spectroscopy measured the changes in the surface crystallinity of cellulose resulting from weathering, both natural and artificial. Both techniques revealed an increase in the crystallin...

Journal: :Applied and environmental microbiology 2007
S Uroz C Calvaruso M P Turpault J C Pierrat C Mustin P Frey-Klett

To date, several bacterial species have been described as mineral-weathering agents which improve plant nutrition and growth. However, the possible relationships between mineral-weathering potential, taxonomic identity, and metabolic ability have not been investigated thus far. In this study, we characterized a collection of 61 bacterial strains isolated from Scleroderma citrinum mycorrhizae, t...

Journal: :Ecological applications : a publication of the Ecological Society of America 2009
Molly A Palmer Michael Graves Thegn N Ladefoged Oliver A Chadwick T Ka'eo Duarte Stephen Porder Peter M Vitousek

Prior to European contact in 1778, Hawaiians developed intensive irrigated pondfield agricultural systems in windward Kohala, Hawai'i. We evaluated three potential sources of nutrients to windward systems that could have sustained intensive agriculture: (1) in situ weathering of primary and secondary minerals in upland soils; (2) rejuvenation of the supply of rock-derived nutrients on eroded sl...

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