tailieunhanh - Encyclopedia of Global Resources part 90

Encyclopedia of Global Resources part 90 provides a wide variety of perspectives on both traditional and more recent views of Earth's resources. It serves as a bridge connecting the domains of resource exploitation, environmentalism, geology, and biology, and it explains their interrelationships in terms that students and other nonspecialists can understand. The articles in this set are extremely diverse, with articles covering soil, fisheries, forests, aluminum, the Industrial Revolution, the . Department of the Interior, the hydrologic cycle, glass, and placer mineral deposits. . | 818 Nitrogen and ammonia Global Resources Web Sites Natural Resources Canada Canadian Minerals Yearbook 1994 Niobium http smm-mms busi-indu cmy-amc content 1994 . Geological Survey Mineral Information Niobium Columbium and Tantalum Statistics and Information http minerals pubs commodity niobium See also Alloys Igneous processes rocks and mineral deposits Minerals structure and physical properties of Nuclear energy Pegmatites Placer deposits Steel Tantalum. Nitrogen and ammonia Category Mineral and other nonliving resources Where Found Nitrogen gas N2 constitutes 78 percent of the Earth s atmosphere. There are deposits of potassium nitrate in India and of sodium nitrate in Chile but nitrogen ranks only thirty-third among the elements in crustal abundance with an average concentration of percent by weight. Natural gas petroleum and coal contain nitrogen and all plants and animals contain nitrogen in the form of proteins. The human body is about 3 percent nitrogen by weight. Ammonia occurs as ammonium chloride salt in volcanic ejecta but industrially produced ammonia is the predominant form used. Ammonia from sewage agricultural runoff and industrial activities can be a water pollutant. Primary Uses The largest use of nitrogen compounds urea ammonium nitrate ammonium phosphates nitric acid and ammonium sulfate is in fertilizer for crops such as wheat corn and soybeans. Nitrogen gas is used as a protective gas in the food electronics and metals industries. Although fertilizer uses are predominant ammonia is also used as a refrigerant and as a chemical intermediate in the manufacture of nitric acid nitrogencontaining plastics and fibers polyamides polyacr y-lonitrile and polyurethane and explosives. Technical Definition Nitrogen symbol N atomic number 7 belongs to Group 15 of the periodic table of the elements. The element has two naturally occurring isotopes and an atomic weight of . Nitrogen occurs as a colorless