tailieunhanh - Encyclopedia of Global Resources part 27

Encyclopedia of Global Resources part 27 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. . | 230 Cobalt Global Resources cially regarding oil and gas production. The 1990 reauthorization established coastal nonpoint source pollution control plans and required the Environmental Protection Agency to establish uniform national guidelines for controlling nonpoint source pollution in coastal areas. The act was further amended in 1996 1998 and 2004 to regulate aquaculture facilities and to research the effects of algal blooms and hypoxia. Jerry E. Green See also Coastal engineering Land management Land-use planning Land-use regulation and control National Oceanic and Atmospheric Administration Population growth. Cobalt Category Mineral and other nonliving resources Where Found Cobalt is widely distributed in the Earth s crust in many ores but only a few are of commercial value the most important of these are arsenides and sulfides. The world s major sources are in the Democratic Republic of the Congo Australia Canada Zambia Russia and Cuba. Primary Uses The largest use of cobalt is in superalloys alloys designed to resist stress and corrosion at high temperatures. Other important uses are in magnetic alloys for motors meters and electronics and as a binder in cemented carbides and diamond tools. Technical Definition Cobalt abbreviated Co atomic number 27 belongs to Group VIII of the transition elements of the periodic table and resembles iron and nickel in many chemical and physical properties. It has one naturally occurring isotope with an atomic weight of . Cobalt as a metal is lustrous and silver y with a bluish tinge. It has an allotropic form that is stable only above 417 Celsius. Its density is grams per cubic centimeter it has a melting point of 1 495 Celsius and a boiling point of 3 100 Celsius. Cobalt is known to exist in more than two hundred ores. These are invariably associated with nickel and often also with cop per and lead. Cobalt is tougher stronger and harder than nickel and iron although less hard than iridium and rhodium. It is .