Encyclopedia of Global Resources part 72 pptx

Kazakhstan will continue to be a major player in the global oil market. Perhaps the crowningillustrationof oil’s significance to the Kazakh economy is President Nursultan Nazarbayev’s ambitious “Kazakhstan 2030” campaign. This directive seeks to vault Kazakhstan into the world’s fifty most economically developed counties. Perhaps not coincidentally, Kazakhstan’s oil production is expected to peak in 2030. Natural Gas While not nearly as significant to Kazakhstan’s global resources as its oil deposits, natural gas is also an important resource, particularly in satisfying local demand. Kazakhstan’s production of naturalgas(nearly 28 trillion cubic meters in 2007) pales incomparisonto neighboring Russia (654 trillion cubic meters), Turk- menistan (69 trillion cubic meters), and Uzbekistan (65 trillion cubic meters). Production is significant, however, placing Kazakhstan twenty-fifth among natural-gas-producing countries, between Pakistan and Venezuela. While much of the natural gas production fulfills domestic consumption, Kazakhstan does export more than 8 trillion cubic meters, ranking it twenty-third in the world between Brunei and the United ArabEmirates. Kazakhstan’s importance tothe global economy with respect to natural gas, however, stems from its substantial anticipated future production. Its natural gas reserves, in 2008, estimated to be 2.8 trillion cubic meters (1.6 percent of the world total), rank Kazakhstan eleventh in the world. Because Kazakhstan consumes slightly more natural gas than it produces (and also exports large amounts), it im- ports nearly 11billioncubicmeters from neighboring Uzbekistan. Kazakhstan’s large area and inadequate internal natural gas transport infrastructure necessi- tate this import from Uzbekistan to serve the southern industrial and urban centers of Shymkent and Alma-Ata. Plans have been introduced to construct a gas pipeline linking Kazakhstan’s gas fields with China’s western province of Xinjiang. Coal Kazakhstan is a major producer of coal and possesses large coal reserves. Kazakhstan ranks as the world’s tenth largest coal producer.Estimates indicate that its coal reserves rank Kazakhstan eighth in the world. While domestic coal consumption of 78 short tons(in 2006) makes Kazakhstan a major consumer, the re - maining 28 tons of coal it produces are exported. Kazakhstan was an important coal producer for the Soviet Union, though production declined after the country gained independence. However, production has risen from its 1999 low. More than one-half of Kazakhstan’s Soviet-era subsurface coal mines have closed, falling victim to restructuring difficulties, numerous fatal mine accidents, and difficulty in attract- ing foreign investment. Coal is an important energy source within Kazakhstan, as coal-powered plants produce 80 percent of the country’s electricity. The country’s coalfields, located primarily in the central Qaraghandy region, are somewhat unique in the amount of coal-bed methaneemitted.In fact, Kazakh- stan is one of the only countries that actively harness this gas for energy purposes. Uranium Kazakhstan’s uranium-related history includes its pri- macy as a source of the mineral for the Soviet Union and as thehomeof the Soviet nuclear weaponstesting ground at the Polygon site near the northeastern city of Semey. Given the global concern over the burning of fossil fuels, greenhouse-gas emissions, and contri- butions to climate change and global warming, uranium is poised to become an increasingly important energy source infuture decades, particularly as global electricity consumption is expected to double. Fur- thermore, more than thirty nuclear reactorsarebeing built around the world, with an additional several hundred in advanced planning stages. As a result, Kazakhstan is well placed to capitalize on current and future demand, as it is the world’s third largest uranium producer, behind Canada and Australia, and is home to the world’s second largest uranium reserves, behind only Australia. Estimates put Kazakhstan’s uranium endowment at 17 percent of the world’s total. Kazakhstan’s proximate location to the world’s two most populous countries is also seen as an important aspect of its future uranium production and export. Increases in nuclear power in China and In- dia are viewed as important markets for Kazakhstan’s uranium. Unique features of Kazakhstan’s uranium stocks include accessibility, high quality, and ease of extraction. By using the in situ leaching method, in which water and sulfuric acid free the mineral from surrounding rock, Kazakhstan is able to extract uranium at a relatively low cost. The arrest of Mukhtar Dzhakishev, former chief executive officer of the national uranium company Kazatomprom, is widely believed to be politically motivated. This arrest, and others like it, illustrates one aspect of the risky envi - 658 • Kazakhstan Global Resources ronment associated with foreign investment in Ka- zakhstan’s mining sector. Chromium Taking into account both current production and estimated reserves, Kazakhstan may be the global economy’s most important source of chromium. Al- ternatively referred toas chrome ore or chromite, the mineral has a unique blend of corrosion resistance, hardness, and bright finish, which make it an indis- pensable input for jet-engine turbine blades, fuel- efficient engine, and, most important for the global economy, stainless steel. Kazakhstan produces 17 percent of the world’s chromium, second only to South Africa. Regarding future production, Kazakhstan has the largest reserves ofchromium in theworld (26 percent of the world total), far outpacing South Africa (15 percent of world total) and India (3 percent of world total). Global demand for chromium largely mirrors that for stainless steel, the most important end use of chromium. In fact, there is not a substitute for chromium in the production of stainless steel, a fact that solidifies Kazakhstan’s importance in the global chromium market. Kazkhrom, a chromium extraction company, nearly one-third of which is owned by the Kazakhstan government, is the world’s second- largest chromium producer. About one-half of production is exported; the other half is used in Kazakh- stan’s sizable steel industry. Quantifying chromium’s contribution to the Kazakhstaneconomyisdifficult as the mineral is not an openly traded commodity and exchange details are not made public. Global short- ages of chromium have, however, resulted from demand greatly outstripping supply. As a result, commodity prices were estimated to have doubled between 2007 and 2008. China—the world’s largest steel producer and experiencing increases in con- struction, industrialization, and overall economic growth—is seen as an important current and future market for Kazakhstan’s chromium. Other Resources Kazakhstan, ranked eighth in theworldinproduction of manganese, is estimated to be home to the world’s Global Resources Kazakhstan • 659 Workers stand behind vessels containing uranium, one of Kazakhstan’s main natural resources. (Getty Images) second largest manganese reserves. As of 2009, pro - duction was at only 20 percent capacity, and all manganese mining operations within Kazakhstan were foreign owned. Kazakhstan is the eleventh largest producer among countries of lead and has the fourth largest lead reserves. Someestimates claim that global lead resources will be exhausted by 2050,so Kazakhstan maybecome a leading producer in coming decades. Much of the lead used now,however, is produced by recycled materials. Home to the world’s eleventh largest copper reserves, Kazakhstan is also the world’s eleventh largest producer. Kazakhmys, the largest copper producer in Kazakhstan, exports 85 percent of its final product to China. Kazakhmys also producessilver, gold, and zinc. Kazakhstan is the world’s seventh largest producer of zinc and is home to the world’s fifth largest reserves. While zincisan important input inthegalvani- zation of steel and the production of brass, its prices have fallen steadily as global demand has dropped precipitously. The Kazakhstan metals company Ka- zakhmys, in response to poor market conditions, an- nounced in June, 2009, that it was suspending operations at its Balkhash zinc production facility. Kazakhstan is the eleventh largest producer of iron ore in the world and is home to the world’s seventh largest reserves. Production has been declining in re- cent years, however, and much of thecountry’s deposits are considered of low-grade quality. Kazakhstan’s other resources include important animal and plant resources. The Caspian Sea, for example, is home to the endangered beluga sturgeon, noted for its production of world-class caviar. Apples appear to have originated in Kazakhstan, where forests of wild apples offer a vast genetic “library” for this valuable plant. Agricultural researchers have collected seeds from Kazakhstan’s apple forests in anattemptto conserve the biodiversity of apples in case the mono- culture varieties that dominate world markets should face catastrophic disease from pests, fungus, or vi- ruses. Kristopher D. White Further Reading Fergus, Michael, and Janar Jandosova. Kazakhstan: Coming of Age. London: Stacey International, 2004. Koven, Peter. “Kazakhstan Unrest Dims Uranium Ore SharesForty Percent.” Financial Post, May 28,2009. Kramer, Andrew E. “Capitalizing on Oil’s Rise, Ka - zakhstan Expands Stake in Huge Offshore Proj - ect.” The New York Times, January 15, 2008. Lustgarten, Abrahm. “Nuclear Power’s White-Hot Metal.” Fortune 157, no. 6 (March 31, 2008). Papp, John F. “Chromium.” In 2006 Minerals Yearbook. Denver, Colo.: U.S. Geological Survey, 2008. Peck, Anne E. Economic Development in Kazakhstan: The Role of Large Enterprises and Foreign Investment. New York: Routledge, 2004. Pomfret, Richard. “Kazakhstan’s Economy Since In- dependence: Does the Oil Boom Offer a Second Chance for Sustainable Development?”Europe-Asia Studies 57, no. 6 (2005): 859-876. Serafin, Tatiana. “Emerging Market Gold Mine.” Forbes 177, no. 6 (March 27, 2006). Timmons, Heather. “Kazakhstan: Oil Majors Agree to Develop Field.” The New York Times, February 26, 2006. See also: Chromium; Coal; Nuclear energy; Oil and natural gas reservoirs; Strategic resources; Uranium. Kyanite Category: Mineral and other nonliving resources Where Found Because metamorphosed high-alumina shales are common in the mountain belts of the world, kyanite group minerals are widely distributed. However, con- centrations of the minerals in reasonably large crystal size are required for economic production. Major kyanite ore reserves are found in the southern Appa- lachian Piedmont and in India. Sillimanite has been mined inIndia, Australia, and South Africa. Large deposits of commercial-grade andalusite occur in France, South Africa, and North Carolina. Primary Uses Kyanite minerals are usedin high-temperature metallurgical processes. They are also used in high-strength porcelain manufacture. Technical Definition Kyanite is an aluminum silicate mineral, Al 2 SiO 5 , also written Al 2 O 3 C SiO 2 . Two other minerals, sillimanite and andalusite, have identical composition but crys - tallize in different forms determined by the tempera - 660 • Kyanite Global Resources ture and pressure at the time of crystallization. The three minerals are polymorphs (different forms) of Al 2 SiO 5 and constitute the kyanite, or sillimanite, group of minerals. Description, Distribution, and Forms Kyanite crystallizes as blade-shaped crystals with vitre- ous luster and white to blue color. Sillimanite is most commonly finely fibrous and brown in color. Andalu- site occurs as elongate, cigar-shaped crystals in a vari- ety of colors.Kyanite-group minerals occur mostcom- monly in metamorphosed high-alumina shales. Relatively high pressures and temperatures produce kyanite, intermediate pressures and high temperatures produce sillimanite, and low temperatures and pressures produce andalusite. History Kyanite has beenmined in many parts of the world.In the past,it was treasured for its blue color. Some tradi- tions indicate kyanite has healing powers. Obtaining Kyanite Kyanite minerals require varying amounts of prepara- tion before use. Massive aggregates of kyanite and sillimanite that occur in India have been sawed or carved to desired shapes, but kyanite group mineral resources in Europe and North America normally require separation of the minerals from associated quartz, micas, and other minerals, resulting in a gran- ular product. The granules, which do not adhere to one another, are mixed with various materials, usually including fireclay and water, to produce a moldable product that can be used as mortar between refractory bricks or molded into bricks or other useful shapes. As a high-temperature furnace lined with “green” (unfired) superduty refractory bricks is heated, the kyanite group minerals in the green brick and mortar convert to mullite. Uniquely, the volume of mullite and silica glass resulting from the conversion of kyanite to mullite is about18percent greater than the original volume of kyanite. The volume increase occurs at about the same temperature that other materials are shrinking in volume, and this phenomenon tends to mechanically stabilize the furnace lining. Therefore, there is a significant advantage to including raw kya - nite in the green products. Uses of Kyanite The kyanite group minerals are used as superduty refractories in high-temperature metallurgical processes, especially steel production, and in high- strength porcelain products, typically automobile spark pluginsulators. On heating to about1,400° Cel- sius, the kyanite group minerals alter to mullite (3Al 2 O 3 C 2SiO 2 ) plus silica glass.Mulliteremains stable and strong to 1,810° Celsius. The kyanite group minerals are therefore very desirable as refractories in steel and glass furnace linings and asmaterialsforkiln furniture (product supports) in high-temperature ce- ramic manufacture. Kyanite group minerals compete economically with synthetic mullite refractories.Synthetic mullite is produced by heating or fusing an appropriate mix- ture of high alumina and siliceous materials. Near Americus, Georgia, naturally occurring mixtures of Global Resources Kyanite • 661 Kyanite is used in metallurgical processes and can range in color from white to blue. (©John Carter/Dreamstime.com) bauxite and kaolin—and at Niagara, New York, alu - mina and glass-grade silica sand—are used to produce synthetic mullite. Robert E. Carver Web Site U.S. Geological Survey Kyanite http://minerals.usgs.gov/minerals/pubs/ commodity/kyanite/index.html#myb See also: Ceramics; Clays; Metamorphic processes, rocks, and mineral deposits; Minerals, structure and physical properties of; Orthosilicate minerals. Kyoto Protocol Category: Laws and conventions Date: Produced in June, 1992; adopted for use on December 11, 1997; entered into force February 16, 2005 The Kyoto Protocol is an environmental treaty created to stabilize greenhouse gases (GHGs) in the atmo- sphere. It is a protocol to the United Nations Frame- work Convention on Climate Change, which was produced at the United Nations Confer- ence on Environment and Development in Brazil from June 3 to 14, 1992. Background In 1987, the Montreal Protocol was established, creating a treaty to phase out production of a major group of industrial gases, including chlorofluoro- carbons, that deplete the ozone layer. The Kyoto Protocol was established to enhance energy efficiency in areas not covered in the Montreal Protocol. It en- courages research and reform, reducing emissions of GHGs and methane, as well as facilitation of measures to address climate change. The protocol includes twenty-eight articles addressing climate change in transport, energy, and industry sectors and stresses the need for research, publications, and periodic review of the protocol. Provisions The Kyoto Protocol establishes legally binding commitments for the reduction of carbon dioxide (CO 2 ), methane (CH 4 ), nitrous oxide (N 2 0), and sulfurhexa- fluoride (SF 6 ) for developed countries for the post- 2000 period and control of hydrofluorocarbons (HFCs) and perfluorocarbons (PFCs), produced by Annex I (industrialized) nations. Cuts in these gases are measured against a baseline (from either 1990 or 1995). As of 2008, 183 parties had ratified the Kyoto Pro- tocol with specific goals of quantified emissions lim- itation or reduction commitments of 5.2 percent in comparison to 1990, collectively. The developed countries committed to reducing emissions of the six key GHGs through cuts of as much as 8 percent. For some countries, stabilization of emissions was the goal. By 2005, progress had to be demonstrated in all countries, and targets were to be achieved between 2008 and 2012. Impact on Resource Use In order for the impact of the protocol to be evalu- ated, countries were required to submit information on their climate change programs and promote public awareness, education, and training. Monitoring and compliance procedures were designed to deter- mine whetherparties were fulfilling their obligations. 662 • Kyoto Protocol Global Resources Upon the adoption of the Kyoto Protocol, chairman Raul Estrada Oyuela shakes hands with a delegate, while other diplomats celebrate with applause. (AP/Wide World Photos) A national system for estimating the GHG emissions was also required. The protocol called for an expert team to review the inventories and manage their GHG portfolios, which all nations in Annex I and most of the non-Annex I countries established. Ultimately, theprotocol has forced countries toad- dress their overuse of fuels responsible for global warming and gave them sufficient reason to reduce local and regional air pollution. Compliance was expected to reduce petroleum dependence and ineffi- ciencies in energy production and use. Further, the economic burden of implementing the policies were expected to be worth the investment, especially when considering the socioenvironmental costs ofnot abid- ing by the protocol. Germany, for example, reduced its GHG emissions by 22.4 percent between 1990 and 2008, and in 2004, France shut downitslast coal mine todecrease its CO 2 emissions. Overall, the Kyoto Protocol demonstrated that the world could produce the same amount of energy with less coal, more gas, and the use of more renewable sources of energy. Gina M. Robertiello See also: Agenda 21; Climate Change and Sustain- able Energy Act; Edison Electric Institute; Green- house gases and global climate change; Intergovern- mental Panelon Climate Change; Montreal Protocol; United Nations climate change conferences; United Nations Framework Convention on Climate Change. Global Resources Kyoto Protocol • 663 L La Niña. See El Niño and La Niña Lakes Category: Ecological resources Lakes are inland bodies ofwater thatfilldepressions in the Earth’s surface. They are generally too deep to allow vegetation to cover the entire surface and may be fresh or saline. Background Lakes are standing bodies of water that occupy hol- lows or depressions onthesurface oftheEarth. Small, shallow lakes are usually called ponds, but there is no specific size and depth that are used to distinguish ponds from lakes. The scientific study of the physical, chemical, climatological, biological, and ecological aspects of lakes is known as limnology. Precipitation is the primary source of water for lakes, in the form of either direct runoff by streams that drain into a depression or groundwater that slowly seeps into a lake by passing through subsurface earth materials. Although lakes are generally thought of as freshwater bodies, many lakes in arid regions become very salty because of the high evaporation rate, which concentrates inflowing salts. The Caspian Sea, the Great Salt Lake, and the Dead Sea are classic examples of saline lakes. Although freshwater and saline lakes account for a minute fraction of the world’s water—almost all of itis in the oceans and in glaciers—they are an extremely valuable resource. In terms of ecosystems, lakes are divided into a pelagial (open-water) zone and a litto- ral (shore) zone where macrovegetation grows. Sedi- ments free of vegetation that occur below the pelagial zone are in the profundal zone. The renewal time for freshwater lakes ranges from one to one hundred years. The length of time varies directly with lake volume and average depth,andindi - rectly with a lake’s rate of discharge. The rate of re - newal, or turnover time, for lakes is much less than that of oceans and glacial ice, which is measured in thousands of years. Lake size varies enormously. Lake sizes range from small depressions of a hectare or less to that of the Caspian Sea, the largest in the world, which covers 371,000 square kilometers. This one body of saline water is larger than all of Germany. The Great Lakes of North America (Lakes Superior, Huron, Michigan, Erie, and Ontario) make up the largest continuous mass of fresh water on the planet, with a combined area of more than 245,000 square kilometers—larger than the total area of Great Britain. The largest single freshwater lake in the world is Lake Superior, with a surface area of more than82,000 square kilometers— nearly the size of Ireland. Other major freshwater lakes include Lake Victoria in Africa, Lake Huron, and Lake Michigan, with approximate areas of 69,000, 60,000, and 58,000 square kilometers, respectively. Lake Baikal in Russia not only is the deepest lake in the world (1,620 meters) but also contains the largest amount of fresh water(23,600cubickilometers). This one lake alone contains approximately 20 percent of all of the fresh water in the world. The combined volume, 22,810 cubic kilometers, of all of the five Great Lakes is still less than Lake Baikal. However, Lake Baikal and the Great Lakes account for more than 40 percent of the total amount of fresh water in the world. The second and third largest freshwater lakes in the world in terms of volume are Lake Tanganyika in Africa and Lake Superior, with 18,900 and 12,100 cubic kilometers, respectively. LakeTanganyika is also the second deepest lake in the world (1,433 meters). Lake Titicaca in the AndesMountains of Peru andBo- livia is the highest lake in the world at 3,800 meters elevation, while the Dead Sea in Israel and Jordan is the lowest, at an elevation of 422 meters below sea level. Origins of Lakes Lakes are unevenlydistributedon the Earth’s surface. Nearly half of the world’s lakes are in Canada, and Minnesota is proud of its reputed count of ten thou - sand lakes. Both Canada and Minnesota were deeply affected by continental glaciation during the various stages of the Pleistocene epoch, or Ice Age, which lasted for approximately two million years. Infact, most of the world’s lakes were formed as a consequence of the movement of continental ice sheets during the Pleistocene. For example, the Great Lakes were formed by advancing ice sheets that carved out large basins in the bedrock. In many other instances, existing valleys were eroded and deepened by glacial advance, resulting in the formation of large lakes such as Great Bear Lake and Great Slave Lake in central Canada (31,153 and 27,200 square kilometers, respectively). In some instances, long, narrow valleys were oriented parallel to the movement of the ice sheet. Whenthe ends ofthese valleys became blocked by glacial debris, the basins filled up with water to form long, narrow lakes. The Finger Lakes of western New York State provide an excellent example of this process. Numer- ous small lakes and ponds were formed in kettles, which are small depressions found in glacial deposits called moraines. Blocks of stagnant ice that became trapped in the morainal deposits melted and formed kettle lakes. Minnesota and many other areas in the upper Midwest and central Canada have numerous kettle lakes with this type of origin. Tectonic activity in the crust of the Earth formed lake basins in a number of ways. For example, faulting results in rift valleys that can fill with water. The downfaulted block is referred to as a graben and ac- counts for thedeepestlakes in the world,LakesBaikal and Tanganyika. These lakes are also unusual in that they contain a large number of relict endemic species of plants and animals. More than 80 percent of the plant and animal species in Lake Baikal are endemic only to this lake. Examples of graben lakes in the United States include Lake Tahoe, in the Sierra Mountains of California and Nevada, and Pyramid Lake, north of Reno in Nevada. The Truckee River flows from Lake Tahoe into Pyramid Lake. Several large, isolated lake basins have resultedfrom tectonic movements that caused a moderate uplift of the marine seabed. The Caspian Sea and the Aral Sea in central Asia were separated by uplifted mountain ranges in the Miocene epoch (from 5 to 24 million years ago).Lake Okeechobee in central Florida, which is the second largest freshwater lake in the cotermi- nous United States (Lake Michigan is the largest), with an area of 1,890 square kilometers, was a shallow depression in the seafloor when it was uplifted during the Pliocene epoch some 2 to 5 million years ago as part of the formation of the Floridian peninsula. The third major natural cause of lakes is volcanic activity. Lava flows can block stream valleys and form lake basins, and collapsing volcanic cratersform large basins called calderas.Crater Lake inOregon, with an area of 64 square kilometers and a depth of 608 meters (making it the ninth deepest in the world), is a well-known example of a caldera lake. The fourth type of natural origin occurs in humid regions underlain by limestone. This type of rock is susceptible to disso- lution by percolating water. In time, the limestone goes into solution, and the result is a conical and cir- cular sinkhole. These sinkhole lakes arevery common in limestone areas of the Balkans and the midwestern United States and in central Florida. Oxbow lakes develop in meandering stream channels of gently slop- ing alluvial floodplains that have been abandoned by lateral shifts of the river. These are common in the floodplain of the lower Mississippi River. Lakes, whatever the nature of their origin, are ephemeral features on the Earth’s surface. In contrast to many other landforms on the Earth, such as moun - tains and valleys, lakes are transient. Drier climatic Global Resources Lakes • 665 Aerial view of Lake Huron, one of North America’s five Great Lakes. conditions, erosion of an outlet, natural and human- induced sedimentation, waterdiversion,and nutrient inflow inexorably result in a short life span of hundreds to thousands of years. On a geological time- scale, this longevity is extremely short. Lake Stratification Solar heating of a lake results in thermal stratification, which isa major factor in lakestructure. This process is the most important physical event in the annual cycle of a lake. Thermal stratification is common in many midlatitude lakes that are deeper than approximately 10 meters. During the high Sun or summer months, an epilimnion—a warm, lighter, circulating, and relatively turbulent layer—develops in the surface waters; it has a range of thickness of about 2 to 20 meters. A lower level ofdenser, cooler, andrelatively quiet water develops below the epilimnion. The vertical extent of this hypolimnion level can be large or small, depending on the depth of the lake. The thermocline, or metalimnion, forms a zone of transition between the two layers where the temperature changes abruptly. It is generally several meters in thickness. The stratification is not caused by the temperature change but rather by the difference in the densities of the water in the epilimnion (lighter) and the hypolimnion (heavier). As the fall season approaches, heat loss from the surface exceeds heat inputs, and the epilimnion cools, becomes denser, and mixeswith the deeper layers. Eventually, all of the water in the lake is included in the circulation as thefall turnover begins. Most lakes experience a seasonal cycle ofstratification and mixing that is a key componentoftheirecology. Reservoirs Reservoirs are artificial lakes; they range from small farm or fish ponds ofless than ahectare insize to massive impoundments. The three largest reservoirs in terms of capacity are Lake Kariba on the Zambezi River, which forms the boundary between Zimbabwe and Zambia in Africa; Bratsk on the Angara River in Siberia; and Lake Nasser on the Nile in Egypt. The largest reservoirs in the United States are Lake Mead and Lake Powell on the Colorado River. Reservoirs are built for hydropower, flood control, navigation, water supply, low flow maintenance for water quality purposes, recreation, or any combination thereof. Reser- voir management is a specialized field, since water re - leases and storage requirements must fit in with the operating schedule for each system and watershed. Although dams and reservoirs have brought many benefits to society, they are associated with several environmental problems. For example, the dams on the Columbia River in the Pacific Northwest inhibit the ability of salmon to return upstream where they spawn. Fish ladders have provided only a partial solution to this problem. Large impoundments such as Lake Mead (behind Hoover Dam on the Colorado River) can store so much water that the additional weight on theEarth’s crust has beenlinked to small to moderate earthquakes in parts of Nevada hundreds of kilometersaway. Reservoirs, by design, regulate the flow of water downstream. In the process of doing so, they deny the river its normal seasonal flush of water in the spring, which is necessary for a healthy aquatic ecosystem. As a means of addressing this flushing problem on the Grand Canyon portion of the Colo- rado River, a large amount of water was released from Lake Powell, which is upstream from the Grand Can- yon, in a short period of time so as to replicate the spring flood. Considerable hydropower revenues were lost in this experiment, but there were many benefits to the ecology of the river. Eutrophication The aging ofa lake by biologicalenrichment is known as eutrophication. The water in young lakes is cold and clear, with minimal amounts of plant and animal life. The lake is then in the oligotrophic state. As time goes on, streams that flow into the lake bring in nutrients such as nitrates and phosphates, which encourage aquatic plant growth. As the fertility in the lake increases, the plant and animal life increases, and organic remains start accumulating on the bottom. The lake is in the process of becoming eutrophic. Silt and organic debris continue to accumulate over time, slowly making the lake shallower. Marsh plants that thrive in shallow water start expanding and gradually fill in the original lake basin. Eventually the lake becomes a bog and then dry land. This natural aging of a lake can take thousands of years, depending uponthesize of the lake,the local climate, and other factors. However, human activitiescan substantially accelerate the eutrophication process. Among the problems causedbyhumans are the pollution of lakesbynutrients from agricultural runoff and poorly treated wastewater from municipalities and in- dustries. The nutrients encourage algal growth, which clogs the lake and removes dissolved oxygen from the water. The oxygen is needed for other forms of aquatic 666 • Lakes Global Resources life. The lake enters a hypereutrophic state as declining levels of dissolved oxygen result in incomplete oxida- tion of plant remains, a situation that eventually causes the death of the lake as a functioning aquatic ecosystem. In a real sense, the lake chokes itself to death. Climatic Effects Lakes moderate local climates. Since thespecific heat of water is five times that of dry land, lakes ameliorate cold-air-mass intrusions in midlatitude regions. The resultant extension of the frost-free period can be extremely beneficial to agriculture. The successful vine- yards on the shores of the Finger Lakes in New York and the fruit-tree belts in upper New Yorkjust south of Lake Ontario are a well-known example of this bene- fit. Even inFlorida,the presence of Lake Okeechobee helps the agricultural areas on the southern and southeastern shores; cold air from the northwest is warmed as it passes over the lake. The Great Lakes are associated with a “lake effect” that results in additional snow falling in those areas where cold Canadian air masses pass over the lakes from the northwest in the winter, pick up moisture from the relatively warmer water, andthenprecipitate the snow on the southern and eastern shores of the lakes. The amounts of snow deposited during these routine occurrences can be substantial. Robert M. Hordon Further Reading Brönmark, Christer, and Lars-Anders Hansson. The Biology of Lakes and Ponds. 2d ed. Oxford, England: Oxford University Press, 2005. Burgis, Mary, and Pat Morris. The Natural History of Lakes. Illustrations by Guy Troughton. New York: Cambridge University Press, 1987. Cole, Gerald A. Textbook of Limnology. 4th ed. Prospect Heights, Ill.: Waveland Press, 1994. Dempsey, Dave. On the Brink: The Great Lakes in the Twenty-first Century. East Lansing: Michigan State University Press, 2004. Dodson, Stanley I. Introduction to Limnology. New York: McGraw-Hill, 2005. Håkanson, Lars, and M. Jansson. Principles of Lake Sedimentology. New York: Springer, 1983. Margalef, R., ed. Limnology Now: A Paradigm of Plane- tary Problems. New York: Elsevier, 1994. Thornton, Kent W., Bruce L. Kimmel, and Forrest E. Payne, eds. Reservoir Limnology: Ecological Perspec - tives. New York: Wiley, 1990. Thorson, Robert M.Beyond Walden: The Hidden History of America’s Kettle Lakes and Ponds. New York: Walker, 2009. Wetzel, Robert G. Limnology: Lake and River Ecosystems. 3d ed. San Diego, Calif.: Academic Press, 2001. Web Sites U.S. Environmental Protection Agency Aquatic Biodiversity: Lakes, Ponds, and Reservoirs http://www.epa.gov/bioiweb1/aquatic/lake-r.html U.S. Environmental Protection Agency Clean Lakes http://www.epa.gov/owow/lakes See also: Dams; Ecosystems; Eutrophication; Glaci- ation; Groundwater; Hydrology and the hydrologic cycle; Streams and rivers; Water supply systems; Wet- lands. Land ethic Categories: Environment, conservation, and resource management; social, economic, and political issues Land ethic is a nonanthropocentric ethical perspective on the relationship betweenhumanbeingsandthe natural environment. Definition Land ethic is a nonanthropocentric perspective of ethics, in which Homo sapiens is seen as simply a mem- ber of the ecosystem and not as the master of the Earth. It is also the title of one of Aldo Leopold’s es- says, included in A Sand County Almanac (1949), one of the most influential books ever published on the ethics of modern nature conservation and one of the founding texts of environmental ethics. From this perspective, other nonhuman entities have in their own right a place on the planet, a concept which im- poses onhumans the duty to respect and preserve the integrity and stability of the natural environment for present and future generations of all living beings. Overview The relevant moral community or the entities to whom a particular set of moral duties and obligations Global Resources Land ethic • 667 . earthquakes in parts of Nevada hundreds of kilometersaway. Reservoirs, by design, regulate the flow of water downstream. In the process of doing so, they deny the river its normal seasonal flush of water in. valleys, lakes are transient. Drier climatic Global Resources Lakes • 665 Aerial view of Lake Huron, one of North America’s five Great Lakes. conditions, erosion of an outlet, natural and human- induced. Kyanite Global Resources ture and pressure at the time of crystallization. The three minerals are polymorphs (different forms) of Al 2 SiO 5 and constitute the kyanite, or sillimanite, group of minerals. Description,