scholarly journals Porosity production in weathered rock: Where volumetric strain dominates over chemical mass loss

2019 ◽  
Vol 5 (9) ◽  
pp. eaao0834 ◽  
Author(s):  
Jorden L. Hayes ◽  
Clifford S. Riebe ◽  
W. Steven Holbrook ◽  
Brady A. Flinchum ◽  
Peter C. Hartsough
Keyword(s):  
Mass Loss ◽  
Sierra Nevada ◽  
Volumetric Strain ◽  
Critical Zone ◽  
Chemical Components ◽  
Relative Importance ◽  
Conventional View ◽  
Biotite Weathering ◽  
Physical And Chemical ◽  
Geophysical Measurements

Weathering in the critical zone causes volumetric strain and mass loss, thereby creating subsurface porosity that is vital to overlying ecosystems. We used geochemical and geophysical measurements to quantify the relative importance of volumetric strain and mass loss---the physical and chemical components of porosity---in weathering of granitic saprolite of the southern Sierra Nevada, California, USA. Porosity and strain decrease with depth and imply that saprolite more than doubles in volume during exhumation to the surface by erosion. Chemical depletion is relatively uniform, indicating that changes in porosity are dominated by processes that cause strain with little mass loss. Strain-induced porosity production at our site may arise from root wedging, biotite weathering, frost cracking, and the opening of fractures under ambient topographic stresses. Our analysis challenges the conventional view that volumetric strain can be assumed to be negligible as a porosity-producing mechanism in saprolite.

scholarly journals Anisovolumetric weathering in granitic saprolite controlled by climate and erosion rate

Geology ◽  
2021 ◽  
Author(s):  
Clifford S. Riebe ◽  
Russell P. Callahan ◽  
Sarah B.-M. Granke ◽  
Bradley J. Carr ◽  
Jorden L. Hayes ◽  
...  
Keyword(s):  
Mass Loss ◽  
Multiple Regression ◽  
Sierra Nevada ◽  
Land Surface ◽  
Erosion Rate ◽  
Volumetric Strain ◽  
Physical Strain ◽  
Physical Weathering ◽  
Soil Weathering ◽  
Erosion Rates

Erosion at Earth’s surface exposes underlying bedrock to climate-driven chemical and physical weathering, transforming it into a porous, ecosystem-sustaining substrate consisting of weathered bedrock, saprolite, and soil. Weathering in saprolite is typically quantified from bulk geochemistry assuming physical strain is negligible. However, modeling and measurements suggest that strain in saprolite may be common, and therefore anisovolumetric weathering may be widespread. To explore this possibility, we quantified the fraction of porosity produced by physical weathering, FPP, at three sites with differing climates in granitic bedrock of the Sierra Nevada, California, USA. We found that strain produces more porosity than chemical mass loss at each site, indicative of strongly anisovolumetric weathering. To expand the scope of our study, we quantified FPP using available volumetric strain and mass loss data from granitic sites spanning a broader range of climates and erosion rates. FPP in each case is ≥0.12, indicative of widespread anisovolumetric weathering. Multiple regression shows that differences in precipitation and erosion rate explain 94% of the variance in FPP and that >98% of Earth’s land surface has conditions that promote anisovolumetric weathering in granitic saprolite. Our work indicates that anisovolumetric weathering is the norm, rather than the exception, and highlights the importance of climate and erosion as drivers of subsurface physical weathering.

Pyrolysis Kinetics of Physical and Chemical Components of Wood using Isoconversion Method

2012 ◽  
Author(s):  
Wenjia Jin ◽  
Kaushlendra Singh ◽  
John W Zondlo ◽  
Jingxin Wang ◽  
Jagpinder Singh Brar
Keyword(s):  
Chemical Components ◽  
Pyrolysis Kinetics ◽  
Physical And Chemical ◽  
Kinetics Of ◽  
Isoconversion Method

scholarly journals A Strategy to Synthesize Multilayer Graphene in Arc-Discharge Plasma in a Semi-Opened Environment

Materials ◽  
2019 ◽  
Vol 12 (14) ◽  
pp. 2279 ◽  
Author(s):  
Hai Tan ◽  
Deguo Wang ◽  
Yanbao Guo
Keyword(s):  
Discharge Plasma ◽  
Arc Discharge ◽  
Chemical Reduction ◽  
Chemical Properties ◽  
Chemical Vapor ◽  
Chemical Components ◽  
Multilayer Graphene ◽  
Whole Process ◽  
Hazardous Chemical ◽  
Physical And Chemical

Graphene, as the earliest discovered two-dimensional (2D) material, possesses excellently physical and chemical properties. Vast synthetic strategies, including chemical vapor deposition, mechanical exfoliation, and chemical reduction, are proposed. In this paper, a method to synthesize multilayer graphene in a semi-opened environment is presented by introducing arc-discharge plasma technology. Compared with previous technologies, the toxic gases and hazardous chemical components are not generated in the whole process. The synthesized carbon materials were characterized by transmission electron microscopy, atomic force microscopy, X-ray diffraction, and Raman spectra technologies. The paper offers an idea to synthesize multilayer graphene in a semi-opened environment, which is a development to produce graphene with arc-discharge plasma.

scholarly journals Decomposition of Organic Chemical Components in Wood by Tropical Xylaria Species

2020 ◽  
Vol 6 (4) ◽  
pp. 186
Author(s):  
Takashi Osono
Keyword(s):  
Mass Loss ◽  
Leaf Litter ◽  
Tree Species ◽  
Chemical Components ◽  
Organic Chemical ◽  
Klason Lignin ◽  
Wood Decomposition ◽  
Recalcitrant Compounds ◽  
Initial Content

The ability of Xylaria species obtained from tropical wood and leaf litter to cause a mass loss of lignin and carbohydrates in wood was examined in vitro with pure culture decomposition tests. The mass loss of wood of four tree species caused by nine Xylaria isolates ranged from 4.5% to 28.4% of the original wood mass. These Xylaria isolates have a potential ability to decompose lignin and other recalcitrant compounds, collectively registered as acid unhydrolyzable residues or Klason lignin in wood. The origin of isolates (i.e., isolates from wood versus leaf litter) did not affect the mass loss of acid unhydrolyzable residue in wood. The Xylaria isolates tested generally caused a selective decomposition of polymer carbohydrates in wood in preference to acid unhydrolyzable residue. The mass loss of acid unhydrolyzable residue caused by Xylaria isolates varied with the tree species of the wood and was negatively related to the initial content of acid unhydrolyzable residue in wood, implying the limiting effect of lignin and recalcitrant compounds on wood decomposition by Xylaria isolates.

Defining Conditions for the Etching of Silicon in an Inductive Coupled Plasma Reactor

1999 ◽  
Vol 605 ◽  
Author(s):  
H. Ashraf ◽  
J. K. Bhardwaj ◽  
E. Guibarra ◽  
S. Hall ◽  
J. Hopkins ◽  
...  
Keyword(s):  
Plasma Reactor ◽  
Etching Rate ◽  
Critical Dimension ◽  
High Rate ◽  
Chemical Components ◽  
Effective Strategies ◽  
Variation Of Parameters ◽  
Process Support ◽  
Dimension Control ◽  
Physical And Chemical

AbstractIn high-density fluorinated plasma processes, the mechanisms that fundamentally limit the etching of silicon are poorly understood. In an effort to improve our understanding of limits to the performance of such systems, the etching of silicon wafers in an inductive coupled plasma reactor, using SF6, has been studied. A systematic empirical investigation has allowed us to define many of the experimental parameters that control the etching rate.There is little temperature dependence of etching which suggests a diffusion limited process. Systematic variation of parameters controlling the rate of etching: total pressure in the reactor, flow rate, partial pressure of reactive species and the rf power supplied to the discharge enable us to accurately define the performance of the system. Experiments, which segregate the physical and chemical components of the etching process, support the conclusion that etching is dominated by electrically neutral species. These various results are interpreted in terms of accepted models for the reactive chemistry in plasmas containing SF6.The MEMS industry is placing ever greater demands on etching processes, and there is a need to achieve the high degrees of anisotropy, and critical dimension control, at high etch-rates. The approach outlined allows us to develop effective strategies for evolving improved systems for the high rate plasma etching of silicon.

Decomposition of needle litter and its organic chemical components: theory and field experiments. Long-term decomposition in a Scots pine forest. III

1984 ◽  
Vol 62 (12) ◽  
pp. 2880-2888 ◽  
Author(s):  
Björn Berg ◽  
Göran I. Ågren
Keyword(s):  
Chemical Composition ◽  
Mass Loss ◽  
Scots Pine ◽  
Field Experiments ◽  
Average Rate ◽  
Chemical Components ◽  
Organic Chemical ◽  
Labile Fraction ◽  
Lignin Fraction ◽  
Scots Pine Forest

Scots pine needles were collected and field incubations were begun in the autumn of 6 consecutive years. The incubated needles were sampled three times a year and analysed for mass loss and chemical composition. The longest incubation time obtained was 1825 days. Four series of needles from a nutrition experiment (three levels of nutrient application and one control) sampled at one occasion were followed in the same way for 1448 days. The logarithm of remaining mass versus time of the pooled samples fits a linear regression well (average rate constant = 0.286 year−1, r2 = 0.963, n = 75). A higher resolution shows, however, that the decay rate decreases with time as the chemical composition changes. To better understand the decomposition process we have formulated a mathematical model for the course of mass loss as a system consisting of two fractions, a readily decomposable (labile) one and a refractory one. The mass loss from the two fractions can be direct or mass can be transferred from the refractory to the labile fraction. The model allows us to calculate the variation of the refractory fraction with time (generally there will always be some labile material in the system) and the decrease of the decomposition rate as a function of time or as a function of the concentration of the refractory fraction. We have found it possible to identify the refractory fraction both as the lignin fraction and as the nonsoluble fraction of the needles. The first identification yields a long transient response, whereas the second gives a system rapidly reaching a steady state. In both cases, the decay of the refractory material results in transfer of material to the labile fraction.

Physical and Chemical Controls on the Critical Zone

Elements ◽  
2007 ◽  
Vol 3 (5) ◽  
pp. 315-319 ◽  
Author(s):  
S. P. Anderson ◽  
F. von Blanckenburg ◽  
A. F. White
Keyword(s):  
Critical Zone ◽  
Physical And Chemical

scholarly journals Influence of Physical and Chemical Components on the Physical-Mechanical Properties of Ten Brazilian Wood Species

2020 ◽  
Vol 23 (2) ◽  
Author(s):  
Bárbara Branquinho Duarte ◽  
Francisco Antonio Rocco Lahr ◽  
Antonio Aprigio da Silva Curvelo ◽  
André Luis Christoforo
Keyword(s):  
Mechanical Properties ◽  
Wood Species ◽  
Chemical Components ◽  
Physical And Chemical

scholarly journals Mass loss induction on physical and chemical qualities of ‘murcott’ tangor during cold storage

2015 ◽  
Vol 31 (5) ◽  
pp. 1325-1332 ◽  
Author(s):  
Josuel Alfredo Vilela Pinto ◽  
Fabio Rodrigo Thewes ◽  
Márcio Renan Weber Schorr ◽  
Deiverson Luiz Ceconi ◽  
Auri Brackmann ◽  
...  
Keyword(s):  
Mass Loss ◽  
Cold Storage ◽  
Physical And Chemical
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