4. Atmospheric composition

2017 ◽  
pp. 65-92
Author(s):  
Paul I. Palmer
Keyword(s):  
Ultraviolet Radiation ◽  
Atmospheric Aerosols ◽  
Stratospheric Ozone ◽  
Ultraviolet B ◽  
Atmospheric Composition ◽  
Earth’S Atmosphere ◽  
Stratospheric Ozone Layer ◽  
History Of ◽  
Earth's Atmosphere ◽  
The Impact

Nitrogen, oxygen, and argon represent more than 99.9% of the air we breathe. But Earth’s atmosphere hasn’t always had that composition—it is on at least its third distinctive atmosphere. ‘Atmospheric composition’ provides a brief history of Earth’s atmosphere, before considering the two most important regions of the atmosphere for human survival—the stratosphere and troposphere. The stratospheric ozone layer shields harmful ultraviolet-B light penetrating to the surface, thereby protecting humans and ecosystems from harmful ultraviolet radiation. The troposphere is where billions of people live and breathe. It is also where air pollutants are emitted, wildfires burn, vegetation grows, and where the oceans exchange gases. The impact of atmospheric aerosols and greenhouse gases is also discussed.

History of the Earth’s Atmosphere

1987 ◽  
Author(s):  
Michael I. Budyko ◽  
Alexander B. Ronov ◽  
Alexander L. Yanshin
Keyword(s):  
Earth’S Atmosphere ◽  
History Of ◽  
Earth's Atmosphere

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.

History of the Earth's Atmosphere

Eos ◽  
1988 ◽  
Vol 69 (38) ◽  
pp. 869 ◽  
Author(s):  
Robert A. Berner
Keyword(s):  
Earth’S Atmosphere ◽  
History Of ◽  
Earth's Atmosphere

scholarly journals Stratospheric ozone depletion

2006 ◽  
Vol 361 (1469) ◽  
pp. 769-790 ◽  
Author(s):  
F. Sherwood Rowland
Keyword(s):  
Ultraviolet Radiation ◽  
Ozone Depletion ◽  
Biological Activities ◽  
Stratospheric Ozone ◽  
Ozone Layer ◽  
Ultraviolet B ◽  
Montreal Protocol ◽  
Atmospheric Measurements ◽  
Solar Ultraviolet Radiation ◽  
Solar Ultraviolet

Solar ultraviolet radiation creates an ozone layer in the atmosphere which in turn completely absorbs the most energetic fraction of this radiation. This process both warms the air, creating the stratosphere between 15 and 50 km altitude, and protects the biological activities at the Earth's surface from this damaging radiation. In the last half-century, the chemical mechanisms operating within the ozone layer have been shown to include very efficient catalytic chain reactions involving the chemical species HO, HO 2 , NO, NO 2 , Cl and ClO. The NO X and ClO X chains involve the emission at Earth's surface of stable molecules in very low concentration (N 2 O, CCl 2 F 2 , CCl 3 F, etc.) which wander in the atmosphere for as long as a century before absorbing ultraviolet radiation and decomposing to create NO and Cl in the middle of the stratospheric ozone layer. The growing emissions of synthetic chlorofluorocarbon molecules cause a significant diminution in the ozone content of the stratosphere, with the result that more solar ultraviolet-B radiation (290–320 nm wavelength) reaches the surface. This ozone loss occurs in the temperate zone latitudes in all seasons, and especially drastically since the early 1980s in the south polar springtime—the ‘Antarctic ozone hole’. The chemical reactions causing this ozone depletion are primarily based on atomic Cl and ClO, the product of its reaction with ozone. The further manufacture of chlorofluorocarbons has been banned by the 1992 revisions of the 1987 Montreal Protocol of the United Nations. Atmospheric measurements have confirmed that the Protocol has been very successful in reducing further emissions of these molecules. Recovery of the stratosphere to the ozone conditions of the 1950s will occur slowly over the rest of the twenty-first century because of the long lifetime of the precursor molecules.

Oxygen

2017 ◽  
Author(s):  
Donald Eugene Canfield
Keyword(s):  
Scientific Evidence ◽  
Earth’S Atmosphere ◽  
The Earth ◽  
Evolution Of Life ◽  
History Of ◽  
Earth's Atmosphere ◽  
Book Covers ◽  
Over Time ◽  
The Way

The air we breathe is 21 percent oxygen, an amount higher than on any other known world. While we may take our air for granted, Earth was not always an oxygenated planet. How did it become this way? This book covers this vast history, emphasizing its relationship to the evolution of life and the evolving chemistry of the Earth. The book guides readers through the various lines of scientific evidence, considers some of the wrong turns and dead ends along the way, and highlights the scientists and researchers who have made key discoveries in the field. Showing how Earth's atmosphere developed over time, the book takes readers on a remarkable journey through the history of the oxygenation of our planet.

INFLUENCE OF THE MANAGED FORESTS ON CO2 BALANCE IN EARTH’S ATMOSPHERE

2021 ◽  
Vol 43 (1) ◽  
pp. 54-66
Author(s):  
Gennadiy BULATKIN
Keyword(s):  
Indirect Costs ◽  
Power Input ◽  
Nitrogen Fertilizers ◽  
Total Power ◽  
Natural Form ◽  
Earth’S Atmosphere ◽  
Aspen Tree ◽  
Co2 Balance ◽  
Earth's Atmosphere ◽  
The Impact

Technical energy costs required for forest cultivation, estimation of C-CO2 fluxes in model experiments with coniferous species of pine Pinus sylvestris L. and leaves species, natural form and gene modified clone of the ordinary aspen tree Populus tremula L., have been analyzed. At plantation cultivation of transgenic aspen clone with nitrogen fertilizers indirect costs of technical energy made up 85 % of total power input. A new three-stage method has been developed for assessing the impact of forests on the CO2 balance in the Earth's atmosphere. The final value of CO2 sink from the atmosphere at afforestation depends on the way wood is used.

Influence of ultraviolet-B radiation, stratospheric ozone variability, and thermal stratification on the phytoplankton biomass dynamics in a mesohumic lake

2000 ◽  
Vol 57 (3) ◽  
pp. 600-609 ◽  
Author(s):  
Marguerite A Xenopoulos ◽  
Yves T Prairie ◽  
David F Bird
Keyword(s):  
Phytoplankton Biomass ◽  
Thermal Stratification ◽  
Stratospheric Ozone ◽  
Negative Relationship ◽  
Taxonomic Composition ◽  
Ultraviolet B ◽  
Temporary Increase ◽  
Ultraviolet B Radiation ◽  
Major Shift ◽  
The Impact

Terrestrial ultraviolet radiation (UVR) is highly variable in both space and time, and phytoplankton in the mixed layer may be exposed at irregular intervals to significant daily doses. The influence of the natural UVR on phytoplankton dynamics was investigated in a small mesohumic lake, Lac Cromwell, in the Laurentian Hills by means of a time-intensive (about 60 days) daily study of the relationship between UVR flux and phytoplankton biomass. Following the onset of lake stratification, at which time the epilimnion became shallower than 2.5 m, the study revealed a strong negative relationship between ultraviolet-B radiation (UVB) and algal biomass at the surface (r 2 = 0.61) and at 1 m (r 2 = 0.38). Although this relationship held throughout the stratified period, chlorophyll a concentration declined particularly rapidly (-65%) during a short-lived ozone-thinning period. There was a major shift in the community taxonomic composition during the same period from a typical diatom-chrysophyte spring bloom towards a dinoflagellate-dominated community that was followed by cyanobacteria. Here, we present evidence that the impact of the temporary increase in UVB was intensified by a concurrent lack of mixing, indicating that turbulence and thermal stratification are key components modulating UVB effects in lakes.

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