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Calcium is the fifth most abundant element in the Earth’s crust, of which it makes up roughly 3.6 per- cent. Limestone, largely or entirely composed of calcium carbonate, is generally formed by the deposition and consolidation of the skeletons of invertebrate marine organisms, although some limestones are the result of chemical precipita- tion from solution. Dolostone, composed chiefly of the...
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In command economies, markets are subordinated to the authority of the state. Private property conveys to the owners of capital and resources the right to use their property regard- less of the impact on society or nature. More recently, property refers not to the use of the property but rather to its value. Clearing waterways and digging canals reduced the...
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Chalk is made of the shells of microscopic floating or- ganisms which once lived in the sea. Sodium carbonate minerals are present in associa- tion with dry salt lake deposits in some parts of the world. The most important use of calcite is in the production of cements and lime. The raw materials are ground together, and the mixture is...
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The element cesium makes up only 7 parts per million of the Earth’s crust. Cesium has significant applications in the manufac- ture of photoelectric cells and vacuum tubes. The In- ternational Atomic Energy Agency has also identified cesium 137 as one of the radioactive materials that may be used to make “dirty bombs.”. it may explode in the presence of...
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cubic meters, or almost equal to China’s total annual runoff.. The total hydrological power reserve is esti- mated at 680 million kilowatts, ranking first in the world. Of the total, 380 million kilowatts can be devel- oped to generate 1.9 trillion kilowatt-hours of electric- ity, which contribute a great deal to China’s economic development and the world economy.. China’s vast...
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Clean Air Act. The Clean Air Acts of 1963 and 1970, with subse- quent amendments, are intended to improve air qual- ity in the United States, largely through mandated air quality standards.. The 1963 Clean Air Act (CAA) and its 1965 amend- ments attempted to improve air quality in the United States through federal support of air pollution re- search...
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presence of which would ordinarily cause decay of the plant tissue. A layer of peat in excess of 2 meters in thickness and cov- ering more than 5,000 square kilometers is present in the Dismal Swamp of coastal North Carolina and Vir- ginia.. Such a sequence of rock deposited during a single advance and retreat of the shoreline, termed a...
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Cobalt is widely distributed in the Earth’s crust in many ores, but only a few are of commercial value. The world’s major sources are in the Democratic Re- public of the Congo, Australia, Canada, Zambia, Rus- sia, and Cuba.. Cobalt (abbreviated Co), atomic number 27, belongs to Group VIII of the transition elements of the peri- odic table and resembles...
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“Conservation” generally refers to the use of re- sources found in the natural environment in such a way that the resources will serve humans effectively and will be available to humans for as long as possible.. Humans alter the natural cycling of energy and flow of matter in the Earth’s ecosystem. Natu- ral resources are all of the things that...
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The emphasis of the program is to create synergies and partnerships among the stakeholders in ways that are pro-poor, gender equitable, and envi- ronmentally sustainable.. The major uses of copper are in the electrical industry because of the substance’s ability to conduct electric-. Copper is also utilized extensively in the construction industry especially for plumbing. Most of the remaining copper...
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By 3400 b.c.e., the fossil record shows a marked change in corn, notably increased cob and kernel size, indicating greater domestication.. Extensive attempts at hybridization began in the late nineteenth century, but the increase in yield was usually a disappointing 10 percent or so. One of the hybridizers of the 1920’s was Henry A. Dry milling is a simpler process,...
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The pri- mary function of most dams is to smooth out or regu- late flows downstream of the dam. Flood-control objectives dictate that a dam’s reservoir be as empty as possible so that any excess water from the watershed (the area upstream of the dam that sheds water to it) can be detained or re- tained in the reservoir to...
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their forests, their consumption patterns have led to the continuing deforestation of the tropics.. Clearing of forests without suitable replanting de- creases timber supplies, often leads to potential deg- radation of the soil and water, reduces species diver- sity, and may contribute to long-term climatic change.. Because of reforestation projects, forest cover in the United States and Western Europe began...
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290 • Department of Energy, U.S. Department of Energy. Office of the Under Secretary For Nuclear Security/. Office of the Under Secretary. After the end of the Cold War in 1990, the Depart- ment of Energy deemphasized production of new nuclear weapons and shifted some support to theoret- ical research: particle acceleration experiments at the Department of Energy’s Fermi National...
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In the United States, cool deserts (sagebrush grass and salt-desert shrub types) occur in old lake beds.. Some plants, such as mesquite, have deep root systems that allow access to deep sources of water.. Some plants have dense, shallow root sys- tems that allow them to tap soil water in the soil sur- face from light showers. Some plants, such...
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Diatomite is a soft, chalklike, fine-grained sedimen- tary rock composed primarily of the fossilized silica shells of microscopic algae called diatoms. The word “diatom” comes from Greek diatomos, meaning “cut in half,” because of the two valves.. Three main types of diatomite deposits are recognized in the United States: marine rocks near continental margins, lacustrine rocks formed in ancient lakes...
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drought occurred in the region during the 1950’s, the mid-1970’s, and the late 1980’s. Until the mid-1800’s the only explosive available was black powder, which was lacking in power and created flames that constituted a fire or dust explosion hazard in mines. Although it did find use in the mining industry, the hazard of pre- mature explosions was extreme, and...
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Until the 1960’s, forestry, fish, and wildlife management techniques were aimed at increasing the productivity of single species—usually game species, such as quail and trout, or commercial tree species, such as loblolly pine. As community ecology and ecosystem ecology matured, and as popular concern for the loss of species arose in the 1960’s, natural resource management agen- cies began to...
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31 million square kilometers, which is nearly 21 per- cent of the entire world landmass. The tropics with summer rain zone constitutes, ap- proximately, bands of moist and dry savannas north and south of the equator, 25 million square kilome- ters, in northern and eastern South America, central and southern Africa, India, Southeast Asia, and north- ern Australia and nearby...
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An example of such a seed bank in the United States is the National Plant Germplasm System in Colorado, under the aegis of the Department of Agriculture.. Endangered Species and Medicine. Even though researchers, especially those active during and since the chemical revolution of the eighteenth century, have developed a growing number of artificial drugs that have proved increasingly effective...