The Gaia Hypothesis - Fact or Fancy?

1989 ◽  
Vol 69 (4) ◽  
pp. 759-768
Author(s):  
J.C.A. Craik
Keyword(s):  
Oxygen Content ◽  
Thermodynamic Equilibrium ◽  
Large Scale ◽  
Present Value ◽  
Earth’S Atmosphere ◽  
Gaia Hypothesis ◽  
Earth's Atmosphere ◽  
Scale Properties ◽  
Living Organisms ◽  
Concentric Shell

Many large-scale properties of the biosphere are affected or determined by the activities of living organisms and are maintained at remarkably constant values over long periods. For example, the oxygen content of the atmosphere appears to have been maintained near its present value for hundreds of millions of years, despite the rapid flux of oxygen between production by plants and consumption by animals and decomposing microorganisms. (In this article, I shall use 'biosphere' to denote the whole of the concentric shell of the planet Earth which holds life, and 'biota' to mean all living organisms. Others have sometimes used 'biosphere' to mean the latter.) Lovelock was the first to show clearly how the composition of the Earth's atmosphere, unlike that of Mars or Venus, was held well away from thermodynamic equilibrium by the activities of living organisms (Lovelock, 1983). Other biospheric properties, such as temperature and oceanic pH and salinity, have similarly remained fairly constant despite the existence of large perturbing influences (Lovelock, 1979).

scholarly journals High-resolution spectroscopy and spectropolarimetry of the total lunar eclipse January 2019

2020 ◽  
Vol 635 ◽  
pp. A156
Author(s):  
K. G. Strassmeier ◽  
I. Ilyin ◽  
E. Keles ◽  
M. Mallonn ◽  
A. Järvinen ◽  
...  
Keyword(s):  
Large Scale ◽  
Solar Spectrum ◽  
High Resolution Spectroscopy ◽  
Strong Increase ◽  
Lunar Eclipse ◽  
The Sun ◽  
The Moon ◽  
Earth’S Atmosphere ◽  
The Earth ◽  
Earth's Atmosphere

Context. Observations of the Earthshine off the Moon allow for the unique opportunity to measure the large-scale Earth atmosphere. Another opportunity is realized during a total lunar eclipse which, if seen from the Moon, is like a transit of the Earth in front of the Sun. Aims. We thus aim at transmission spectroscopy of an Earth transit by tracing the solar spectrum during the total lunar eclipse of January 21, 2019. Methods. Time series spectra of the Tycho crater were taken with the Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI) at the Large Binocular Telescope in its polarimetric mode in Stokes IQUV at a spectral resolution of 130 000 (0.06 Å). In particular, the spectra cover the red parts of the optical spectrum between 7419–9067 Å. The spectrograph’s exposure meter was used to obtain a light curve of the lunar eclipse. Results. The brightness of the Moon dimmed by 10.m75 during umbral eclipse. We found both branches of the O2 A-band almost completely saturated as well as a strong increase of H2O absorption during totality. A pseudo O2 emission feature remained at a wavelength of 7618 Å, but it is actually only a residual from different P-branch and R-branch absorptions. It nevertheless traces the eclipse. The deep penumbral spectra show significant excess absorption from the Na I 5890-Å doublet, the Ca II infrared triplet around 8600 Å, and the K I line at 7699 Å in addition to several hyper-fine-structure lines of Mn I and even from Ba II. The detections of the latter two elements are likely due to an untypical solar center-to-limb effect rather than Earth’s atmosphere. The absorption in Ca II and K I remained visible throughout umbral eclipse. Our radial velocities trace a wavelength dependent Rossiter-McLaughlin effect of the Earth eclipsing the Sun as seen from the Tycho crater and thereby confirm earlier observations. A small continuum polarization of the O2 A-band of 0.12% during umbral eclipse was detected at 6.3σ. No line polarization of the O2 A-band, or any other spectral-line feature, is detected outside nor inside eclipse. It places an upper limit of ≈0.2% on the degree of line polarization during transmission through Earth’s atmosphere and magnetosphere.

The Great Oxidation

2017 ◽  
Author(s):  
Donald Eugene Canfield
Keyword(s):  
Oxygen Content ◽  
Atmospheric Chemistry ◽  
Tipping Point ◽  
Earth’S Atmosphere ◽  
Great Oxidation Event ◽  
Earth's Atmosphere ◽  
Geologic Record

This chapter deals with the “great oxidation event” (GOE), which represents a quantum shift in the oxygen content of the atmosphere. It suggests that the GOE represents the evolution of cyanobacteria. According to the geologic record, the oxygen content of Earth's atmosphere increased dramatically around 2.3 billion years ago. Since cyanobacteria likely evolved much earlier, it does not appear that a well-oxygenated atmosphere is a necessary or immediate consequence of the activities of oxygen-producing organisms. Atmospheric chemistry is a slave to the dynamics of the mantle, as the interior and exterior of the planet are connected in a profound way. Indeed, it took half of Earth's history for the mantle to quiet to point where oxygen could accumulate. This, however, represented a watershed, a tipping point if you will, where the chemistry of Earth's surface was forever altered.

scholarly journals MOF-Based Adsorbents for Atmospheric Emission Control: A Review

Processes ◽  
2020 ◽  
Vol 8 (5) ◽  
pp. 613 ◽  
Author(s):  
Nicola Gargiulo ◽  
Antonio Peluso ◽  
Domenico Caputo
Keyword(s):  
Large Scale ◽  
Development Process ◽  
Self Regulation ◽  
Large Section ◽  
Earth’S Atmosphere ◽  
Industrial Implementation ◽  
Laboratory Results ◽  
Adsorption Processes ◽  
Metal Organic ◽  
Earth's Atmosphere

This review focuses on the use of metal–organic frameworks (MOFs) for adsorbing gas species that are known to weaken the thermal self-regulation capacities of Earth’s atmosphere. A large section is dedicated to the adsorption of carbon dioxide, while another section is dedicated to the adsorption of other different gas typologies, whose emissions, for various reasons, represent a “wound” for Earth’s atmosphere. High emphasis is given to MOFs that have moved enough ahead in their development process to be currently considered as potentially usable in “real-world” (i.e., out-of-lab) adsorption processes. As a result, there is strong evidence of a wide gap between laboratory results and the industrial implementation of MOF-based adsorbents. Indeed, when a MOF that performs well in a specific process is commercially available in large quantities, economic observations still make designers tend toward more traditional adsorbents. Moreover, there are cases in which a specific MOF remarkably outperforms the currently employed adsorbents, but it is not industrially produced, thus strongly limiting its possibilities in large-scale use. To overcome such limitations, it is hoped that the chemical industry will be able to provide more and more mass-produced MOFs at increasingly competitive costs in the future.

scholarly journals Large-scale efficient water harvesting using bioinspired micro-patterned copper oxide nanoneedle surfaces and guided droplet transport

2019 ◽  
Vol 1 (10) ◽  
pp. 4025-4040 ◽  
Author(s):  
Vipul Sharma ◽  
Kyriacos Yiannacou ◽  
Markus Karjalainen ◽  
Kimmo Lahtonen ◽  
Mika Valden ◽  
...  
Keyword(s):  
Copper Oxide ◽  
Large Scale ◽  
Cost Effective ◽  
Water Harvesting ◽  
Water Crisis ◽  
Earth’S Atmosphere ◽  
Droplet Transport ◽  
Earth's Atmosphere

As the Earth's atmosphere contains an abundant amount of water as vapors, a device which can capture a fraction of this water could be a cost-effective and practical way of solving the water crisis.

scholarly journals Aerosol and splatter in Dentistry - An Overview

2015 ◽  
Vol 7 (1) ◽  
pp. 28-32
Author(s):  
Dhoom Singh Mehta ◽  
Preetham Pulluri ◽  
Sowmya Nagur Karibasappa
Keyword(s):  
Human Health ◽  
Human Activity ◽  
Urban Ecosystems ◽  
Standard Precautions ◽  
Earth’S Atmosphere ◽  
The World ◽  
Mode Of Transmission ◽  
Earth's Atmosphere ◽  
Living Organisms ◽  
Earth’S Climate

Abstract The environment in which we are surrounded is the sum total of living organisms like animals, plants and microorganisms and their actions which undergo constant changes, especially by human activity. It provides conditions for development and growth and also that of danger and damage. Aerosols are such products seen in the urban ecosystems in various forms. The presence of aerosols in earth's atmosphere can influence earth's climate, as well as human health. As they are omnipresent they form a universal challenge to all the dentists around the world to control their transmission and inhibit their action. Hence, in this article we have reviewed various properties of aerosols, methods of measurements, mode of transmission and standard precautions to be followed. How to cite this article Pulluri P, Karibasappa SN, Mehta DS, Aerosol and Splatter in Dentistry - An overview CODS J Dent 2015;7:28-32.

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