scholarly journals The role of marine silicate weathering in regulating marine carbon cycle over geological time scales

2021 ◽  
Author(s):  
Wei-Li Hong ◽  
Marta Torres ◽  
Kuo-Fang Huang
Keyword(s):  
Carbon Cycle ◽  
Time Scales ◽  
Silicate Weathering ◽  
Geological Time

Processes of the Long-Term Carbon Cycle: Chemical Weathering of Silicates

2004 ◽  
Author(s):  
Robert A. Berner
Keyword(s):  
Carbon Cycle ◽  
Time Scales ◽  
Chemical Weathering ◽  
Continental Drift ◽  
Atmospheric Co2 ◽  
Silicate Weathering ◽  
Geological Time ◽  
Orogenic Uplift ◽  
Steep Slopes ◽  
Primary Minerals

Carbon dioxide is removed from the atmosphere during the weathering of both silicates and carbonates, but, over multimillion year time scales, as pointed out in chapter 1, only Ca and Mg silicate weathering has a direct effect on CO2. Carbon is transferred from CO2 to dissolved HCO3– and then to Ca and Mg carbonate minerals that are buried in sediments (reaction 1.4). In this chapter the factors that affect the rate of silicate weathering and how they could have changed over Phanerozoic time are discussed. Following classical studies (e.g., Jenny, 1941), the factors discussed include relief, climate (rainfall and temperature), vegetation, and lithology. However, over geological time scales, additional factors come into consideration that are necessarily ignored in studying modern weathering. These include the evolution of the sun and continental drift. The aim of this book is to consider all factors, whether occurring at present or manifested only over very long times, that affect weathering as it relates to the Phanerozoic carbon cycle. Within the past decade much attention has been paid to the effect of mountain uplift on chemical weathering and its effect on the uptake of atmospheric CO2, an idea originally espoused by T.C. Chamberlin (1899). The uplift of the Himalaya Mountains and resulting increased weathering has been cited as a principal cause of late Cenozoic cooling due to a drop in CO2 (Raymo, 1991). Orogenic uplift generally results in the development of high relief. High relief results in steep slopes and enhanced erosion, and enhanced erosion results in the constant uncovering of primary minerals and their exposure to the atmosphere. In the absence of steep slopes, a thick mantle of clay weathering product can accumulate and serve to protect the underlying primary minerals against further weathering. An excellent example of this situation is the thick clay-rich soils of the Amazon lowlands where little silicate weathering occurs (Stallard and Edmond, 1983). In addition, the development of mountain chains often leads to increased orographic rainfall and, at higher elevations, increased erosion by glaciers. All these factors should lead to more rapid silicate weathering and faster uptake of atmospheric CO2.

scholarly journals Conserving evolutionary history does not result in greater diversity over geological time scales

2019 ◽  
Vol 286 (1904) ◽  
pp. 20182896 ◽  
Author(s):  
J. L. Cantalapiedra ◽  
T. Aze ◽  
M. W. Cadotte ◽  
G. V. Dalla Riva ◽  
D. Huang ◽  
...  
Keyword(s):  
Time Scales ◽  
Phylogenetic Trees ◽  
Evolutionary History ◽  
Phylogenetic Diversity ◽  
Random Sets ◽  
Geological Time ◽  
The Future ◽  
Species Production

Alternative prioritization strategies have been proposed to safeguard biodiversity over macroevolutionary time scales. The first prioritizes the most distantly related species—maximizing phylogenetic diversity (PD)—in the hopes of capturing at least some lineages that will successfully diversify into the future. The second prioritizes lineages that are currently speciating, in the hopes that successful lineages will continue to generate species into the future. These contrasting schemes also map onto contrasting predictions about the role of slow diversifiers in the production of biodiversity over palaeontological time scales. We consider the performance of the two schemes across 10 dated species-level palaeo-phylogenetic trees ranging from Foraminifera to dinosaurs. We find that prioritizing PD for conservation generally led to fewer subsequent lineages, while prioritizing diversifiers led to modestly more subsequent diversity, compared with random sets of lineages. Importantly for conservation, the tree shape when decisions are made cannot predict which scheme will be most successful. These patterns are inconsistent with the notion that long-lived lineages are the source of new species. While there may be sound reasons for prioritizing PD for conservation, long-term species production might not be one of them.

The Role of Lithology in Silicate Weathering and CO2 Regulation on Rocky Exoplanets

2020 ◽  
Author(s):  
Kaustubh Hakim ◽  
Dan J. Bower ◽  
Meng Tian ◽  
Russell Deitrick ◽  
Pierre Auclair-Desrotour ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Carbon Cycle ◽  
Theoretical Method ◽  
Silicate Weathering ◽  
Weathering Rates ◽  
Rock Water Interaction ◽  
Tectonically Active ◽  
Strong Control

<p>In the decade of JWST, ELT, TMT, PLATO, ARIEL and other specialized telescopes, observations of carbon dioxide in terrestrial exoplanet atmospheres are possible. The amount of carbon dioxide in the atmosphere of a tectonically active planet such as Earth is regulated by the carbonate-silicate cycle (long-term carbon cycle). Silicate weathering provides essential negative feedback to maintain temperate climates on Earth over billions of years. In this study, we model the chemistry of rock-water interaction for different silicate rocks and minerals applicable to both continental and seafloor weathering. We find that weathering rates depend mainly on the partial pressure of carbon dioxide, surface temperature and lithology, and other factors are secondary. This approach allows possessing a theoretical method to determine both continental and seafloor weathering rates on temperate exoplanets that depend little on present-day Earth calibrations. Our study gives a strong control over the connection between atmospheric observables and the carbon cycle. The ultimate goal is to provide an abiotic library of geological false positives of biosignatures.</p>

Carbonation possibilities of Steel slags -- a review

2021 ◽  
Author(s):  
Raghavendra Ragipani ◽  
Sankar Bhattacharya ◽  
Akkihebbal K. Suresh
Keyword(s):  
Carbon Dioxide ◽  
Time Scales ◽  
Carbon Dioxide Sequestration ◽  
Mineral Carbonation ◽  
Geological Time ◽  
The Stability ◽  
Significant Attention

Research pertaining to carbon dioxide sequestration via mineral carbonation has gained significant attention, primarily due to the stability of sequestered \ce{CO2} over geological time scales. Use of industry-derived alkaline wastes...

scholarly journals Impact of tumor-parenchyma biomechanics on liver metastatic progression: a multi-model approach

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yafei Wang ◽  
Erik Brodin ◽  
Kenichiro Nishii ◽  
Hermann B. Frieboes ◽  
Shannon M. Mumenthaler ◽  
...  
Keyword(s):  
Time Scales ◽  
Constitutive Relations ◽  
Elastic Tissue ◽  
Metastatic Progression ◽  
Patient Death ◽  
Metastatic Growth ◽  
Tumor Parenchyma ◽  
Short Time ◽  
Model Approach

AbstractColorectal cancer and other cancers often metastasize to the liver in later stages of the disease, contributing significantly to patient death. While the biomechanical properties of the liver parenchyma (normal liver tissue) are known to affect tumor cell behavior in primary and metastatic tumors, the role of these properties in driving or inhibiting metastatic inception remains poorly understood, as are the longer-term multicellular dynamics. This study adopts a multi-model approach to study the dynamics of tumor-parenchyma biomechanical interactions during metastatic seeding and growth. We employ a detailed poroviscoelastic model of a liver lobule to study how micrometastases disrupt flow and pressure on short time scales. Results from short-time simulations in detailed single hepatic lobules motivate constitutive relations and biological hypotheses for a minimal agent-based model of metastatic growth in centimeter-scale tissue over months-long time scales. After a parameter space investigation, we find that the balance of basic tumor-parenchyma biomechanical interactions on shorter time scales (adhesion, repulsion, and elastic tissue deformation over minutes) and longer time scales (plastic tissue relaxation over hours) can explain a broad range of behaviors of micrometastases, without the need for complex molecular-scale signaling. These interactions may arrest the growth of micrometastases in a dormant state and prevent newly arriving cancer cells from establishing successful metastatic foci. Moreover, the simulations indicate ways in which dormant tumors could “reawaken” after changes in parenchymal tissue mechanical properties, as may arise during aging or following acute liver illness or injury. We conclude that the proposed modeling approach yields insight into the role of tumor-parenchyma biomechanics in promoting liver metastatic growth, and advances the longer term goal of identifying conditions to clinically arrest and reverse the course of late-stage cancer.

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