scholarly journals Cometary impacts into ocean: Thermodynamical equilibrium calculations of high-temperature O2 generation on the early Earth

2002 ◽  
Vol 67 (5) ◽  
pp. 353-365 ◽  
Author(s):  
Pavle Premovic ◽  
Katja Panov
Keyword(s):  
High Temperature ◽  
Earth Science ◽  
Theoretical Models ◽  
Life Forms ◽  
Early Earth ◽  
Present Level ◽  
Thermodynamical Equilibrium ◽  
The Earth ◽  
Primitive Atmosphere ◽  
Equilibrium Calculations

The early Earth?s atmosphere apparently differed from the present atmosphere mainly in its lack of free O2, and this absence is believed to have been indispensable for the origin of early anaerobic life forms. One of the central problems in Earth science is to explain the apparent transition from the primitive atmosphere (free of O2) to the present atmosphere which contains 21% of the gas. Theoretical models suggest that the initial form of O2 in the Earth?s atmosphere may have been H2O, which was converted into atmospheric O2 mainly through photosynthesis. We have investigated an alternative (abiotic) method for the conversion of H2O to O2: a high-temperature shock generated during a cometary impact into an ocean (or on land). The calculations presented here show that 1% of the present level of O2 could have resulted from an icy 1.3x1016 kg comet entering the early (pre-oxygenic) Earth with a velocity of between about 11 and 30 km s-1.

scholarly journals Thermochemical equilibrium calculations of high-temperature O2 generation on the early Earth: Giant asteroid impact on land

2003 ◽  
Vol 68 (2) ◽  
pp. 97-107 ◽  
Author(s):  
Pavle Premovic
Keyword(s):  
High Temperature ◽  
Theoretical Models ◽  
Early Earth ◽  
Present Level ◽  
Initial Form ◽  
Asteroid Impact ◽  
Considerable Debate ◽  
Thermochemical Equilibrium ◽  
Equilibrium Calculations

Earth?s atmosphere is composed primarily of N2 and O2. The origin of free O2 in the early Earth?s atmosphere is still subject of considerable debate.1 Theoretical models suggest that the initial form of free O2 in the atmosphere has been oceanic H2O. Recent computation modeling has suggested that a superheated (ca. 2000 K) H2O vapor atmosphere of 1.4x1021 kg (the present mass of the oceans) lasting for about 3000 y could probably have been formed on Earth by an enormous (ca. 1028 J) asteroid impact. In this report, the occurrence of the thermochemical dissociation of the vapor, creating a primitive oxygenic (ca. 0.1 of the present level (PAL) of free O2) atmosphere.

LIVE PLANTS AS AN ADDITIONAL BOTANICAL COMPONENTOF THE THEMATIC EXPOSITION IN THE EARTH SCIENCE MUSEUM AT MOSCOW STATE UNIVERSITY

2020 ◽  
Vol 42 (4) ◽  
pp. 478-484
Author(s):  
Kirill Golikov ◽  
Ekaterina LAPTEVA ◽  
A. SOCHIVKO
Keyword(s):  
High Altitude ◽  
Plant Communities ◽  
Earth Science ◽  
Life Forms ◽  
Science Museum ◽  
State University ◽  
Structural Components ◽  
The Earth ◽  
The World ◽  
Moscow State University

The article discusses the use of live plants as the botanical exposition component supplement of the “Natural areas” (hall № 17 “Natural zonality and its components” and № 20 “Desert, subtropical, tropical countries, high-altitude zone”) and “Physico-georaphic regions” (hall № 24 “Continents and parts of the world”) departments in order to visualize information presented in the Earth Science Museum. Demonstration of plants originating from different regions of the world representing different life forms and being structural components of various plant communities allows to visually characterizing thematic aspects of an exposition. That in turn reveal such principles of systematic nature organization as ecobiomorphic and phytocenotic.

scholarly journals In-Situ Cosmogenic 14C: Production and Examples of its Unique Applications in Studies of Terrestrial and Extraterrestrial Processes

Radiocarbon ◽  
2001 ◽  
Vol 43 (2B) ◽  
pp. 731-742 ◽  
Author(s):  
D Lal ◽  
A J T Jull
Keyword(s):  
Half Life ◽  
Earth Science ◽  
Chemical Properties ◽  
Radioactive Isotopes ◽  
Earth’S Atmosphere ◽  
The Earth ◽  
Wide Range ◽  
History Of ◽  
Earth's Atmosphere

Nuclear interactions of cosmic rays produce a number of stable and radioactive isotopes on the earth (Lai and Peters 1967). Two of these, 14C and 10Be, find applications as tracers in a wide variety of earth science problems by virtue of their special combination of attributes: 1) their source functions, 2) their half-lives, and 3) their chemical properties. The radioisotope, 14C (half-life = 5730 yr) produced in the earth's atmosphere was the first to be discovered (Anderson et al. 1947; Libby 1952). The next longer-lived isotope, also produced in the earth's atmosphere, 10Be (half-life = 1.5 myr) was discovered independently by two groups within a decade (Arnold 1956; Goel et al. 1957; Lal 1991a). Both the isotopes are produced efficiently in the earth's atmosphere, and also in solids on the earth's surface. Independently and jointly they serve as useful tracers for characterizing the evolutionary history of a wide range of materials and artifacts. Here, we specifically focus on the production of 14C in terrestrial solids, designated as in-situ-produced 14C (to differentiate it from atmospheric 14C, initially produced in the atmosphere). We also illustrate the application to several earth science problems. This is a relatively new area of investigations, using 14C as a tracer, which was made possible by the development of accelerator mass spectrometry (AMS). The availability of the in-situ 14C variety has enormously enhanced the overall scope of 14C as a tracer (singly or together with in-situ-produced 10Be), which eminently qualifies it as a unique tracer for studying earth sciences.

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