Sulfur on Earth

The principal source of sulfur on Earth is deposits of free sulfur occurring mainly in volcanically active regions. The sulfur was initially formed by the reaction between the two volcanic vapors SO2 and H2S to form H20(/) and Ss(s). What volume of SO2, at 0.961 atm and 22.0°C, was needed to form a sulfur deposit of 4.50 X 10 kg on the slopes of a volcano in Hawaii ... 

Kargel, Jeffrey S., Pierre DelmeUe, and Douglas B. Nash. Volcanogenic Sulfur on Earth and lo Composition and Spectroscopy Icarus 142 (November 1999) 249-280. This article compares and contrasts sulfur impurities on lo s surface with sulfur deposits on Earth. 

Hydrogen sulfide is a central participant in the sulfur cycle, the biogeochemical cycle of sulfur on Earth. 

Iron, Fe, the most widely used of all the d-metals, is the most abundant element on Earth and the second most abundant metal in the Earth s crust (after aluminum). Its principal ores are the oxides hematite, Fe203, and magnetite, Fc C)4. The sulfide mineral pyrite, FeS2 (see Fig. 15.11), is widely available, but it is not used in steelmaking because the sulfur is difficult to remove. 

Land/atmospheric interfacial processes which impact climate and biological activity on earth are illustrated in Figure 3. Emissions of carbon dioxide, methane, nitrogen dioxide, and chlorofluorocarbons (CFCs) have been linked to the transmission of solar radiation to the surface of the earth as well as to the transmission of terrestrial radiation to space. Should solar radiation be an internal process or an external driver of the hydrologic cycle, weather, and air surface temperatures Compounds of sulfur and nitrogen are associated with acidic precipitation and damage to vegetation, aquatic life, and physical structures. 

The ocean plays a central role in the hydro-spheric cycling of sulfur since the major reservoirs of sulfur on the Earth s surface are related to various oceanic depositional processes. In this section we consider the reservoirs and the fluxes focusing on the cycling of sulfur through this oceanic node. 

Scientists believe that the sulfur in Venus atmosphere came from volcanic eruptions. Earth has experienced its fair share of volcanic eruptions, too. However, the sulfur from early eruptions on Earth was incorporated into solid sulfur compounds. Indeed, sulfur is an important element found in many of the compounds that make up Earths crust. 

An element is a substance that cannot be broken down into simpler substances by ordinary chemical means. A chemical compound is a substance made up of two or more elements that have been chemically bonded together. Scientists believe that solid sulfur compounds do not exist on Venus like they do on Earth because, at about 900° Fahrenheit (480° Celsius), the surface temperature on Venus is too hot for them to form in the first place. This temperature is well above the melting point of sulfur (235°F [ 113°C]). Therefore, instead of being incorporated into rocks, the sulfur on Venus continues to float around in the atmosphere in the form of the chemical compound sulfur dioxide (S02). 

The clouds around Venus contain relatively large droplets of sulfuric acid, which occasionally rain down on the surface of the planet, or at least they try to, because the temperature is so high that the droplets evaporate before they actually reach the surface. (This almost rain is called virga, the term for any kind of precipitation that evaporates before it reaches the ground.) On Earth, however, the sulfuric acid does not evaporate but falls to the ground as acid rain, an environmental pollutant that can destroy buildings and harm plants and animals. 

Almost 80% of the sunlight that hits Venus is reflected back into space by the thick clouds surrounding the planet before it ever reaches the surface. Even so, temperatures at the surface of Venus are much hotter than those on Earth. However, this is not because Venus is closer to the Sun than the Earth. Scientists believe that the difference in the temperatures of the two planets is due to a runaway greenhouse effect caused by the large amount of sulfur dioxide in Venus atmosphere. 

Cobalt is the 32nd most abundant element on Earth even though it makes up only 0.003% of the Earth s crust. It is not found in the free metallic state, despite being widely distributed in igneous rocks as minerals. Its two most common mineral ores are cobaltite (CoAsS) and erythrite [Co lAsO l ]. These ores are placed in blast furnaces to produce cobalt arsenide (COjAs), which is then treated with sulfuric acid to remove the arsenic. Finally, the product cobalt tetraoxide (Co O ) is reduced by heat with carbon (Co O + C — 3Co + 2COf resulting in cobalt metal. 

ORIGIN OF NAME From the Sanskrit word sulvere and the Latin word sulphurim. ISOTOPES There are a total of 24 isotopes of sulfur all but four of these are radioactive. The four stable isotopes and their contribution to sulfur s total abundance on Earth are as follows S-32 contributes 95.02% to the abundance of sulfur S-33, just 0.75% S-34, 4.21% and S-36, 0.02%. 

Although neodymium is the 28th most abundant element on Earth, it is third in abundance of all the rare-earths. It is found in monazite, bastnasite, and allanite ores, where it is removed by heating with sulfuric acid (H SO ). Its main ore is monazite sand, which is a mixture of Ce, La, Th, Nd, Y, and small amounts of other rare-earths. Some monazite sands are composed of over 50% rare-earths by weight. Like most rare-earths, neodymium can be separated from other rare-earths by the ion-exchange process. 

Ripley EM, Li C (2003) Sulfur isotope exchange and metal enrichment in the formation of magmatic Cu-Ni-(PGE)-deposits. Econ Geol 98 635-641 Robert F (2001) The origin of water on Earth. Science 293 1056-1058... 

The dense clouds in the atmosphere of Venus, which obscure the surface of the planet totally from our view, are evidently composed of a sulfuric acid aerosol. Why are such clouds possible on Venus but not on Earth (See Section 8.1.)... 

The biotransformations of sulfur compounds by microorganisms can have large-scale impacts on global chemistry. As an example, sulfate-reducing bacteria have, throughout histoiy, formed major deposits of elemental sulfur and iron sulfides on Earth, and these processes are continuing today (1). Contemporary sulfate-reduction coupled with the oxidation of reduced inorganic sulfur... 

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