Erosion and erosion control Category: Environment, conservation, and resource management Erosion is the gradual wearing away of the land sur-face by natural agents of water, wind, and i
Trang 1Klyza, Christopher McGrory, and David J Sousa.
American Environmental Policy, 1990-2006: Beyond
Gridlock Cambridge, Mass.: MIT Press, 2008.
Landy, Marc Karnis, Marc J Roberts, and Stephen R
Thomas The Environmental Protection Agency: Asking
the Wrong Questions from Nixon to Clinton New York:
Oxford University Press, 1994
McMahon, Robert The Environmental Protection Agency:
Structuring Motivation in a Green Bureaucracy—
the Conflict Between Regulatory Style and Cultural
Identity Portland, Oreg.: Sussex Academic Press,
2006
Portney, Paul R., and Robert N Stavins, eds Public
Pol-icies for Environmental Protection 2d ed Washington,
D.C.: Resources for the Future, 2000
Rosenbaum, Walter A Environmental Politics and Policy.
7th ed Washington, D.C.: CQ Press, 2008
Samuel, Peter Lead Astray: Inside an EPA Superfund
Di-saster San Francisco: Pacific Research Institute,
2002
Yeager, Peter Cleary The Limits of Law: The Public
Regu-lation of Private Pollution New York: Cambridge
University Press, 1991
Web Site
U.S Environmental Protection Agency
http://www.epa.gov
See also: Carbon; Clean Air Act; Clean Water Act;
Cli-mate Change and Sustainable Energy Act; Ecosystem
services; Endangered species; Environment and
Nat-ural Resources Division; Environmental impact
state-ment; Environmental law in the United States;
Haz-ardous waste disposal; National Environmental Policy
Act; Superfund legislation and cleanup activities;
United Nations Convention on Long-Range
Trans-boundary Air Pollution; Watt, James
Erosion and erosion control
Category: Environment, conservation, and
resource management
Erosion is the gradual wearing away of the land
sur-face by natural agents of water, wind, and ice Eroded
sediments are a major water pollutant The land is
de-graded because the soil that remains is of lower
produc-tivity, and the sediment may damage crops or aquatic
environments Therefore, the control of erosion is an important soil conservation and water quality protec-tion practice.
Background Erosion is a natural process in which water, wind, and ice remove soil particles from the land surface and re-deposit them somewhere else Sediment pollution is the water pollutant comprising the largest volume or mass Erosion also causes the soil to be less productive because the remaining soil is more coarsely textured and of lower fertility Nutrients and pesticides can be released from eroded sediments into streams and lakes
There are three erosion processes: detachment, transportation, and deposition Detachment is the re-moval of soil particles from the soil mass Transporta-tion carries detached particles away from the soil mass The distance can be a few centimeters or hun-dreds of kilometers After the soil is transported, the particles are then redeposited somewhere else (depo-sition)
Classification of Erosion Erosion can be classified in a number of ways Geo-logical erosion is the natural, slow rate of erosion that occurs when the land is protected by its native vegeta-tion Rates are in the range of grams to a few kilo-grams per hectare per year This kind of erosion is responsible for many important present-day land for-mations Accelerated erosion is the rapid erosion that occurs when the native vegetation is removed These rates are in the range of metric tons per hectare per year
The two most important agents of accelerated ero-sion are water and wind Kinds of water eroero-sion are raindrop splash, sheet, rill, and gully erosion Rain-drop splash occurs when rainRain-drops strike soil particles and dislodge them from the rest of the soil mass Falling raindrops have considerable kinetic energy and can easily dislodge particles from bare soils In sheet erosion a thin layer of soil is removed fairly uni-formly across the land surface Rill erosion occurs when small channels (rills) form in the soil These rills are usually parallel to one another, are narrow and shallow, and can be easily removed by ordinary tillage and cultivation practices Rill erosion is responsible for the greatest quantities of soil loss Gully erosion oc-curs when deep, wide channels form that cannot be removed by ordinary tillage and cultivation practices
Trang 2It is the most spectacular because the gullies are easily
seen
Wind erosion is classified according to the way the
soil particles are transported Surface creep is a
roll-ing of large particles across the surface Saltation is a
bouncing of intermediate-sized particles and is
re-sponsible for the largest amount of erosion by wind
Suspension occurs when small particles are picked up
by the wind and carried long distances It is the most
spectacular because the resulting dust cloud is easily
seen
Erosion damage occurs both on-site and off-site
On-site damage occurs because the eroded land is
de-graded by the removal of the most productive parts of
the soil The eroded parts are usually finer textured
and higher in organic matter than the remaining
parts The soil that is left behind is usually coarser
textured Off-site damage occurs because the
trans-ported soil causes damage somewhere else Examples
are smothered crops, decreased storage of drinking
water reservoirs, and the filling in of harbors
Sedi-ment also drastically alters the aquatic life of rivers
and lakes The costs for correcting some of these off-site effects are usually borne by society
Erosion Control Strategies for erosion control involve preventing de-tachment or encouraging deposition before the soil travels very far The most effective and cheapest meth-ods of erosion control are to keep the soil in place and reduce water runoff Erosion control methods may be divided into cultural practices and mechanical con-trol Cultural practices include cropping rotations, tillage methods, and residue management Mechani-cal control includes terraces, sediment control basins, and silt fences A guiding principle in erosion control
is to keep the soil covered, either with growing vegeta-tion or with the remains of vegetavegeta-tion in the form of mulch Another principle is to shorten the slope length Reducing the steepness of a slope is not prac-tical
Erosion control in farming includes contouring, whereby all tillage, planting, and harvesting opera-tions are done across the slope instead of up and
Following a June, 2008, flood, this cornfield in Indiana suffered significant erosion (AP/Wide World Photos)
Trang 3down the slope This practice is most effective for
gen-tle slopes, with a gradient of between 2 and 6 percent
Strip cropping is alternately planting a strip of a row
crop such as corn, soybeans, or cotton and then a strip
of a close-growing crop such as small grain or forage
Field strip cropping is planting the strips straight and
parallel without regard to the slope Contour strip
cropping, planting the strips across the contour of the
slope, will provide erosion control for steeper slopes
up to about 18 percent Terraces are constructed
channels across a slope that reduce the slope length
The channel is at a slight grade so the water is
re-moved slowly and safely Terraces may be cropped or
in permanent vegetation
Grassed waterways are vegetated channels
con-structed where water would cause a gully The
chan-nel is at a slight grade; the grass stabilizes the soil A
water and sediment control basin is a riser pipe
con-nected to a subsurface drain A small dam and an
ori-fice plate in the riser pipe allow the water to pond for
no more than twenty-four hours, which allows
sedi-mentation before the water enters the riser pipe
Con-servation tillage is a method of planting crops in
which last year’s old crop residue (in the form of
straw, stalks, and so on) is not completely
incorpo-rated into the soil but instead is left on the surface as a
mulch At least 30 percent of the soil surface must be
covered by residue to qualify as conservation tillage
No-till is a form of conservation tillage where the crop
is planted without any previous tillage Special
plant-ing equipment is necessary in order to plant through
the crop residue Weed pests are controlled by
herbi-cides rather than by cultivation No-till is very effective
at reducing soil loss
Erosion control for developments and construction
sites includes saving existing vegetation and
disturb-ing only as much land as can be reasonably developed
in a few months Other methods include temporary
seedings, straw mulch, sedimentation basins, silt fences
(plastic sheets staked into the ground), and straw
bales staked in erosive channels
Tom L Zimmerman
Further Reading
Blanco-Canqui, Humberto, and Lal Rattan Principles
of Soil Conser vation and Management London:
Springer, 2008
Brady, Nyle C., and Ray R Weil The Nature and
Prop-erties of Soils 14th ed Upper Saddle River, N.J.:
Prentice Hall, 2008
Montgomery, David R Dirt: The Erosion of Civilizations.
Berkeley: University of California Press, 2007
Morgan, R P C Soil Erosion and Conservation 3d ed.
Malden, Mass.: Blackwell, 2005
Schwab, Glenn O., Delmar D Fangmeier, and
Wil-liam J Elliot Soil and Water Management Systems 4th
ed New York: Wiley, 1996
Toy, Terrence J., George R Foster, and Kenneth G
Renard Soil Erosion: Processes, Prediction, Measure-ment, and Control New York: John Wiley & Sons,
2002
Web Sites School of Geography, Queen’s University Belfast, Northern Ireland
Soil Erosion Site http://soilerosion.net U.S Department of Agriculture Soil Quality Resource Concerns: Soil Erosion http://soils.usda.gov/SQI/publications/files/ sq_two_1.pdf
U.S Geological Survey Erosion
http://www.usgs.gov/science/
science.php?term=353 See also: Conservation; Deforestation; Dust Bowl; Environmental degradation, resource exploitation and; Farmland; Land management; Soil; Soil man-agement
Ethanol
Categories: Products from resources; plant and animal resources
Where Found Ethanol, a biofuel, is produced by carbohydrate fer-mentation processes, hydration of ethylene, and, to a lesser extent, reduction of acetaldehyde obtained from acetylene
Primary Uses Ethanol—also known as ethyl alcohol, grain alcohol,
or spirits—has traditionally found many uses in the chemical industry: for the preparation of numerous esters vital to many polymer industries, for the
Trang 4duction of diethyl ether (also called ether or ethyl
ether), and as a major solvent and extractant
How-ever, it has been best known for thousands of years as
the primary alcohol component in alcoholic
bever-ages and, since the 1970’s, as a potentially significant
source of transportation fuel, either as a gasoline
re-placement or as a blend fuel stretching available
pe-troleum supplies
Technical Definition
Ethanol is a colorless liquid with a mild and
character-istic aroma and taste It has a boiling point of 78.3°
Celsius and a melting point of−114.5° Celsius At 20°
Celsius it has a density of 0.7894 gram per milliliter
and a refractive index of 1.3614 Its molar mass is
46.07 grams Ethanol is completely soluble in water
and most organic solvents It has a flash point of 8°
Celsius and is thus highly flammable
Description, Distribution, and Forms
Alcohol obtained from fermentation processes is
gen-erally included with other fermentation products and
extracts from the carbohydrate-rich grains, fruits, and
so on that are the raw materials for the multitudinous
alcoholic beverages produced and consumed on
Earth Alcohol produced by yeast fermentation is
ob-tained at a maximum concentration of 14 percent;
therefore, alcoholic beverages other than beer and
nonfortified wines require the addition of
concen-trated alcohol, which is obtained by distilling dilute
alcohol from the fermentation of molasses and other
sugar sources In the United States and other highly
industrialized countries, the alcohol added to
bever-ages has increasingly been produced by other
methods
Ethanol is also used in large quantities for chemical
synthesis in the organic chemical industry It is used
for the preparation of numerous esters vital to many
polymer industries and for the production of diethyl
ether (also called ether or ethyl ether), a major
sol-vent and extractant Other synthetic procedures lead
to the manufacture of acetaldehyde, acetic acid, ethyl
halides, and acetonitrile, which are in turn employed
for the preparation of drugs, explosives, adhesives,
pesticides, detergents, synthetic fibers, and other
sub-stances Ethanol itself is used in vast quantities as an
extractant or solvent
For some time, ethanol has been added to gasoline
in winter to reduce air pollution, an advantage of
eth-anol that has been viewed as particularly valuable
since the Kyoto Protocol (1997) and other interna-tional agreements obligated their signors to reduce the carbon emissions associated with internal com-bustion engines Thus, the United States and other oil-importing countries have frequently explored and,
to some degree, pursued the “gasohol” option of com-bining ethanol with varying amounts of gasoline
History The fermentation of various fruits and other products
of the soil into drinking alcohol can produce pleasant tastes and, in the minds of people throughout the globe and for a very long part of history, a pleasurable effect Based on archaeological discoveries, there is evidence of alcoholic imbibing as early as the sixth century b.c.e
Historically, ethanol has been used as a home fuel source, albeit more recently than as a beverage In the 1820’s, for example, a blend of ethanol and turpen-tine was utilized as lamp fuel in the majority of Ameri-can homes Subsequently, natural gas and electricity displaced ethanol in home use in the United States and Europe, but it is still used in rural areas of the de-veloping world for lighting and cooking It is also widely employed as a part of everyday life in American and European homes as rubbing alcohol and as a sol-vent in chemical products
Ethanol was used to power cars—especially in West-ern Europe—well before the Model T rolled off the first assembly line in 1908, driven by a motor based on
an 1860 internal combustion engine developed in Germany to run on ethanol However, before the first Model T was produced, the discovery of oil in the United States in the 1880’s and the high tax that Con-gress enacted on industrial alcohol during the Civil War had combined to render the production of etha-nol for transportation purposes both uneconomical and unnecessary Both the Prohibition era in the United States (1919-1933), which tainted the home production of ethanol for fuel purposes as “closet moonshining,” and the discovery of deep pools of cheap oil in the Middle East during the period be-tween World War I and World War II pushed ethanol further off the market as a source of transportation fuel until the 1973 energy crisis
Obtaining Ethanol Beverage alcohol is produced from a great variety of sources, including grains, potatoes, and fruit, but fer-mentation-based industrial alcohol is almost entirely
Trang 5obtained by yeast fermentation of molasses Molasses
(50 percent sucrose residue from sugar processing or
cornstarch) is diluted with water to approximately 15
percent and under slightly acidic conditions is
fer-mented by yeast to give 14 percent ethanol Fractional
distillation of the solution yields the commercial
product: 95 percent ethanol Approximately 9 liters of
blackstrap molasses are needed to make 3.785 liters of
190-proof ethanol
Although ethylene hydration was known in the
early part of the nineteenth century, it did not
be-come an industrial process until 1929; today, it is the
dominant method of producing ethanol Ethylene,
obtained from the thermal cracking of petroleum
fractions or from natural gas separation processes, is
treated with complex phosphoric acid-based catalysts
at temperatures above 300° Celsius and steam at
pres-sures of thousands of kilograms per square
centime-ter The ethanol can be fractionally distilled, and the
residual ethylene can be recycled Ethylene can also
be passed into concentrated sulfuric acid, and after
hydrolysis, the ethanol can be distilled from the diluted sulfuric acid
Uses of Ethanol Despite ethanol’s importance in the produc-tion of alcoholic beverages and its continued employment in various sectors of the chemi-cal industry, its utility as a means of reducing petroleum dependency has commanded the most commentary and controversy since
1973, when Arab states embargoed oil ship-ments to countries supporting Israel in the Yom Kippur War
Whether corn or sugarcane is used as eth-anol’s feedstock, concern exists that the ex-panded cultivation of both of these crops will greatly increase both air and water pollution The indictment is especially levied against corn, because its cultivation requires the most pesticides and insecticides of any crop grown
in the United States The “pesticide cock-tail”—composed of four weed killers, three insecticides, and two fungicides—produces
a toxic effect known to kill wildlife, and its runoff damages subsoil streams and, hence, threatens U.S supply of drinking water In-creasing the production of ethanol increases environmental costs So too does burning it
in internal combustion engines, in which— depending on the gasohol mixture of ethanol and petroleum—ethanol fuels can produce more than twice as much ground ozone as gasoline Meanwhile,
in the short term, reallocating existing corn produc-tion to meet a growing demand for ethanol inflates the cost of corn and of everything depending on it This includes the price of corn-fed beef, milk drawn from corn-fed dairy cows, and the powdered milk that the United States exports to meet nourishment needs
in poor countries of the developing world Nonethe-less, the United States, which has subsidized biofuels since 1978, is committed, under its Energy Indepen-dence and Security Act of 2007, to the goal of produc-ing 136 billion liters of ethanol by 2022—a fourfold increase over the amount produced in 2008
Issues also exist concerning the actual fuel savings available from an E90 (10 percent ethanol, 90 percent petroleum) gasohol mixture used in the United States Planting and harvesting corn and processing it into ethanol involve significant use of fuel, which has
to be considered in assessing overall petroleum
A worker in Brazil harvests sugarcane, which can be used to produce ethanol
fuel (AP/Wide World Photos)
Trang 6ings through the widespread use of ethanol-petroleum
solutions as gasoline There is also the issue of
kilometers-per-liter savings in ethanol versus
conven-tional gasoline Ethanol burns cleaner than
tradi-tional gasoline in terms of carbon gases, but it also
burns faster, meaning that it requires more energy to
provide the same energy output as its fossil-fuel kin
Brazil has evaded these efficiency issues by utilizing
sugarcane harvested by cheap labor as its feedstock
and by mandating the sale after 2007 of only flexible
fuel vehicles (FFVs) capable of burning fuels
con-taining very high levels of ethanol (up to 85 percent
ethanol and beyond) Consequently, coupled with its
domestic oil production, Brazil has become
indepen-dent of foreign oil For other countries, and especially
those locked into E90 or even E85 mixtures, concerns
over actual fuel savings as well as environmental
dam-age from the use of corn- and sugarcane- derived
etha-nol continue to linger
In the democratic world of pluralistic bargaining in
public policy, these feedstocks that have nonetheless
been favored over the use of switchgrass and other
cel-lulosic sources of ethanol in the production of
gaso-line, despite the two to three times greater reduction in
greenhouse gases possible by using cellulosic biofuels
Existing internal-combustion-engine automobiles and
trucks can run, without major modifications, on E85,
so the automotive industry has had reasons to support
the development of the fuel, especially when
alterna-tives have involved government mandates to retool to
produce solar- or electric-powered cars The
petro-leum industry, too, supports ethanol, which will
main-tain the demand for petroleum, as opposed to
alterna-tive energy technologies in the transportation field,
in which more than one-half of all petroleum used in
the United States is consumed Above all, agricultural
states with an interest in reviving their sagging
agricul-tural communities and the large farming corporations
that own most farming land in the United States have
had reason to lobby diligently on behalf of the ethanol
industry Thus, whenever the focus has been on the
high cost of imported fuels or reducing carbon
emis-sions associated with automobile use, bills requiring
the use of corn-based ethanol have been introduced in
the U.S Congress and have been enacted into law
William J Wasserman, updated by Joseph R Rudolph, Jr.
Further Reading
Blume, David Alcohol Can Be a Gas! Fueling an Ethanol
Revolution for the Twenty-first Century Santa Cruz,
Calif.: International Institute for Ecological Agri-culture, 2007
Boudreaux, Terry Ethanol and Biodiesel: What You Need
to Know McLean, Va.: Hart Energy, 2007.
Brune, Michael Coming Clean: Breaking America’s Ad-diction to Oil and Coal San Francisco: Sierra Club
Books, 2008
Freudenberger, Richard Alcohol Fuel: A Guide to Mak-ing and UsMak-ing Ethanol as a Renewable Fuel Gabriola
Island, B.C.: New Society, 2009
Goettemoeller, Jeffrey, and Adrian Goettemoeller Sus-tainable Ethanol: Biofuels, Biorefineries, Cellulosic Bio-mass, Flex-Fuel Vehicles, and Sustainable Farming for En-ergy Independence Maryville, Mo.: Prairie Oak, 2007 Minteer, Shelley, ed Alcoholic Fuels Boca Raton, Fla.:
CRC/Taylor & Francis, 2006
Mousdale, David M Biofuels: Biotechnology, Chemistry, and Sustainable Development Boca Raton, Fla.: CRC
Press, 2008
Pahl, Greg Biodiesel: Growing a New Energy Economy 2d
ed White River Junction, Vt.: Chelsea Green, 2008
Paul, J K., ed Ethyl Alcohol Production and Use as a Motor Fuel Park Ridge, N.J.: Noyes Data, 1979.
Rothman, Harry, Rod Greenshields, and Francisco
Rosillo Callé Energy from Alcohol: The Brazilian Expe-rience Lexington: University Press of Kentucky,
1983
Shaffer, Brenda Energy Politics Philadelphia:
Univer-sity of Pennsylvania Press, 2009
Web Sites Alternative Fuels and Advanced Vehicles Data Center, U.S Department of Energy
Ethanol http://www.afdc.energy.gov/afdc/ethanol/
index.html Economic Research Service, U.S Department of Agriculture
Ethanol Expansion in the United States: How Will the Agricultural Sector Adjust?
http://www.ers.usda.gov/Publications/FDS/2007/ 05May/FDS07D01/fds07D01.pdf
See also: Biofuels; Brazil; Corn; Energy economics; Energy Policy Act; Gasoline and other petroleum fu-els; Internal combustion engine; Oil and natural gas chemistry; Peak oil; Petrochemical products; Petro-leum refining and processing; Plant domestication and breeding; Resources for the Future; Synthetic Fuels Corporation
Trang 7European Union Natura 2000
Categories: Laws and conventions; organizations,
agencies, and programs
Date: Birds Directive, April 2, 1979; Habitats
Directive, May 21, 1992
Natura 2000 was established to protect endangered
species and regions in the European Union.
Background
The geography of the European Union includes nine
different biogeographical regions This large diversity
of European ecosystems and landscapes offers a
vari-ety of different habitats for fauna and flora: arctic and
high-alpine rocks and glaciers, areas of moderate
cli-mate, marine ecosystems, and arid areas and deserts
Estimates indicate that more than 40 percent of
mam-mals, 15 percent of bird species, and 45 percent of
reptiles in Europe are endangered or threatened
While policies for environmental protection and
nature conservation in protected areas have a rather
long history, environmental protection and nature
conservation policies were not accounted for in the
founding documents of the European Union, such as
the Treaty of Rome (1958) At the beginning of the
1970’s, after the United Nations Conference on the
Human Environment in Stockholm, the European
Commission finally developed environmental policy
programs The Single European Act (1985) and, later,
the Treaty of Amsterdam (1997) included
environ-mental protection in the European treaties The Birds
Directive, emphasizing the conservation of birds, was
passed in 1979; however, the Habitats Directive,
estab-lishing a European network of protected areas, was
not established until 1992 Hence, the European
Union’s Natura 2000 stipulations are part of the
Euro-pean Union’s Sustainable Development Strategy and
of the Environment Action Programme of the
Euro-pean Community, the latter of which has multiple
edi-tions The importance of biodiversity conservation
also has been widely acknowledged in many
Euro-pean Union policies of other fields, such as in the
Eu-ropean Spatial Planning Strategy and the Common
Agricultural Policy
Provisions
The Birds Directive and the Habitats Directive can be
considered the fundamental documents of joint
Eu-ropean Union nature conservation policies The Hab-itats Directive is based on two policies A network of protected areas (Natura 2000 network) has been es-tablished in all member countries, and a strict frame-work for species conservation has been instituted In-dividual member countries are no longer free to decide which nature conservation policies should be pursued if the ecosystems or species endangered or threatened are of community interest However, all member states established their own legal regulations regarding nature conservation much earlier than the joint European framework
The Habitats Directive aims at maintaining biodi-versity by means of a common framework for the con-servation of wildlife (fauna and flora) and of habitats
of community interest Member states are obliged to protect “special protection areas” (SPAs) and “sites of community interest” (SCIs) The directive includes several appendixes where biodiversity elements of community interest are listed, such as natural habi-tats, animal and plant species, and the definition of
“priority” or “strict protection” habitats and species European Union member countries who find habitats
or species of community interest on their territory are obliged to set up conservation areas and management plans and to report to the European Commission about the concrete conservation policies For in-stance, SPAs (Natura 2000 sites) are established based
on the annex of the Habitats Directive, reported by the member state to the European Commission, which includes the site in a list of habitats of commu-nity interest When this has been done, the area is es-tablished as protected Failure of any EU member country to report sites of community interest is sub-ject to charges before the European Court of Justice
An important provision of Natura 2000 is that member states are obliged to guarantee that habitats
of community interest are conserved and any deterio-ration of the habitat is avoided Member states also have to initiate the management of landscapes and habitats of special importance for the migration, dis-persal, and genetic exchange of wildlife; establish strict protection of threatened fauna and flora; ex-plore possibilities of reintroducing extinct wildlife; and prevent the nonselective taking, killing, or cap-turing of wildlife listed in the directive Even if the member state does not formally establish a Natura
2000 site for a priority habitat or species, it is neverthe-less protected under European Union law
The Natura 2000 regulations not only provide for
Trang 8the conservation of biodiversity but also establish the
possibilities for co-financing conservation measures
Implementation of Natura 2000 is estimated to cost
about 6.1 billion euros ($8.6 billion) per year One of
the financial instruments set up for co-financing is the
“LIFE+ Nature and Biodiversity” program It is
specifi-cally designed to contribute to the implementation of
Natura 2000 in member states and to support the
es-tablishment and management of protected areas
The European Union and its member states are
sig-natories of the Convention on Biological Diversity
(CBD) The European Union has also committed
it-self to the goal of halting biodiversity loss In order to
support this goal, the European Commission adopted
a Biodiversity Action Plan in 2006, which followed
earlier strategies such as the Biodiversity Strategy of
1998 The strategy encompasses the European Union’s
commitment to conserving global biodiversity,
ad-dressing issues of biodiversity and climate change,
and implementing a comprehensive knowledge base
regarding the conservation of biodiversity Natura
2000 may serve as a nature conservation model for
other parts of the world
Impact on Resource Use
The Natura 2000 regulations are progressive in terms
of their strict regulatory framework and the concept
of establishing a consistent, coherent, and
representa-tive European ecological network of protected areas
Furthermore, the number of sites set up is impressive
The following are based on 2008 figures: In terms of
the Birds Directive, there are 5,044 SPAs covering an
area of 517,896 square kilometers (10.5 percent of the
area of the European Union and 531 marine sites
cov-ering 66,084 square kilometers The Habitats
Direc-tive has 21,612 SCIs covering an area of 655,968
square kilometers (13.3 percent of the area of the
Eu-ropean Union) and 1,294 marine sites covering an
area of 87,505 square kilometers However, the
appli-cation of the directives in the individual member
states varies and ranges from around 7 percent of
the national territory for SCIs (United Kingdom) up
to 31.4 percent (Slovenia) While the Natura 2000
frameworks provide a coherent and strong basis for
conserving biodiversity, they need to be implemented
effectively in all member states Many areas of
com-munity interest are still “paper parks” without
con-crete management plans or funds for administering
the European Union directives’ requirements The
Biodiversity Action Plans, published assessments of the EU’s biodiversity policies, revealed that it was un-likely that the European Union would be able to meet its aims of halting biodiversity loss by 2010 Policies therefore have to concentrate on the finalization of the Natura 2000 network, provide adequate financial resources for establishing and managing the sites, and implement the necessary action and management plans in the member countries Of specific impor-tance in this context is the support of Natura 2000 sites in the new European Union member countries
in Central and Eastern Europe that significantly con-tribute to the natural endowment of the European Union Funding programs for capacity building is im-portant because the management of protected areas
is an emerging interdisciplinary professional field
Michael Getzner
Further Reading
Bromley, Peter Nature Conservation in Europe: Policy and Practice New York: Spon, 1997.
European Communities The European Union’s Biodi-versity Action Plan: Halting the Loss of BiodiBiodi-versity by 2010—and Beyond Luxembourg: Office for
Offi-cial Publications of the European Communities, 2008
Keulartz, Jozef, and Gilbert Leistra, eds Legitimacy in European Nature Conservation Policy: Case Studies in Multilevel Governance New York: Springer, 2008.
Rosa, H D., and J M Silva “From Environmental Eth-ics to Nature Conservation Policy: Natura 2000 and
the Burden of Proof.” Journal of Agricultural and En-vironmental Ethics 18, no 2 (2005): 107-130.
Web Sites Eionet The European Topic Centre on Biological Diversity http://biodiversity.eionet.europa.eu/
European Commission Nature and Biodiversity http://ec.europa.eu/environment/nature/
index_en.htm
See also: Austria; Belgium; Biodiversity; Denmark; Endangered species; France; Germany; Greece; Italy; The Netherlands; Norway; Poland; Portugal; Spain; Sweden; United Kingdom
Trang 9Category: Pollution and waste disposal
Eutrophication is the overenrichment of water by
nutri-ents; it causes excessive plant growth and stagnation,
which leads to the death of other aquatic life such as fish.
Definition
The word “eutrophic” comes from the Greek eu, which
means “good” or “well,” and trophikos, which means
“food” or “nutrition.” Eutrophic waters are well
nour-ished and rich in nutrients; they support abundant
life Eutrophication refers to a condition in aquatic
systems (ponds, lakes, and streams) in which nutrients
are so abundant that plants and algae grow
uncontrol-lably and become a problem The plants die and
de-compose, and the water becomes stagnant This
ulti-mately causes the death of other aquatic animals,
particularly fish, that cannot tolerate such conditions
Eutrophication is a major problem in watersheds and
waterways such as the Great Lakes and Chesapeake
Bay that are surrounded by urban populations
Overview
The stagnation that occurs during eutrophication is
attributable to the activity of microorganisms growing
on the dead and dying plant material in water As
they decompose the plant material, microbes
con-sume oxygen faster than it can be resupplied by the
at-mosphere Fish, which need oxygen in the water to
breathe, become starved for oxygen and suffocate In
addition, noxious gases such as hydrogen sulfide (H2S)
can be released during the decay of the plant material
The hallmark of a eutrophic environment is one that is
plant-filled, littered with dead aquatic life, and smelly
Eutrophication is actually a natural process that
oc-curs as lakes age and fill with sediment, as deltas form,
and as rivers seek new channels The main concern
with eutrophication in natural resource conservation
is that human activity can accelerate the process and
can cause it to occur in previously clean but
nutrient-poor water This is sometimes referred to as “cultural
eutrophication.” For example, there is great concern
with eutrophication in Lake Tahoe Much of Lake
Tahoe’s appeal is its crystal-clear water However,
de-velopment around Lake Tahoe is causing excess
nu-trients to flow into the lake and damaging the very
thing that attracts people to the lake
The nutrients that cause eutrophication usually come from surface runoff of soil and fertilizer associ-ated with mismanaged agriculture or from domestic and industrial wastes discharged into rivers and lakes Phosphorus (P) and nitrogen (N) are two of the nutri-ents most limiting to plant growth in water When they are supplied, plant growth can explode and eutrophi-cation can occur Phosphorus was one of the major causes of eutrophication in Lake Erie during the 1960’s Before preventative action was taken, the lake was considered to be dying These preventative actions included banning phosphates from laundry detergent and imposing stricter conservation practices on farm-ers to reduce soil erosion in the watfarm-ersheds draining into Lake Erie Many areas now restrict the total amount of phosphorus that can be applied to land that drains into waterways Preventative action also forced sewage treatment facilities to start chemically remov-ing phosphorus from the water they discharged As a result of these actions, phosphorus loading into Lake Erie was cut in half from the 1960’s to the early 1990’s; however, total phosphorus content in Lake Erie rose slightly over the subsequent decade and a half
Mark S Coyne
See also: Ecosystems; Erosion and erosion control; Lakes; Streams and rivers
Evaporites
Category: Mineral and other nonliving resources
Evaporites are sedimentary deposits of salt minerals that crystallize from marine and continental brines Common evaporite minerals include halite (sodium chloride, or table salt), gypsum (hydrated calcium sul-fate), calcite (calcium carbonate), dolomite (calcium-magnesium carbonate), and various borate minerals.
Definition Evaporites form in environments where evaporative water loss from a body of water exceeds, at least peri-odically, the rate of inflow to the body Evaporites oc-cur in all the major continents; the most extensive de-posits are found in North and South America, Europe, and the Middle East Notable North American locali-ties are the Michigan Basin and the Permian Basin of Texas and New Mexico Most rock salt (halite) is mined
Trang 10from evaporites, as is the gypsum used in wallboard
and other construction materials Borate minerals are
used in cleaning agents and in other industrial uses
Other evaporite minerals are important sources for
industrial metals such as magnesium and strontium
Overview
Evaporites are stratified sedimentary deposits
consist-ing of minerals precipitated from salt brines (highly
concentrated salt water) These deposits have formed
on every continent and throughout geologic time,
al-though the Silurian (438 to 408 million years ago) and
Permian (286 to 248 million years ago) periods were
the most prolific times of evaporite formation In
re-cent times evaporite deposition has been relatively
rare The chief factors influencing evaporite formation
are aridity and a closed basin environment in which
water inflow is restricted High air temperatures
gen-erally accompany these conditions, but this is not
al-ways the case For example, recent minor evaporites
are known from the arid regions of Antarctica
Evaporite minerals crystallize from seawater in a
certain order, depending on their relative solubilities
Calcite generally crystallizes first as the amount of
water is reduced by evaporation Gypsum follows, with
halite precipitating when only about one tenth of the
original solution is left More soluble minerals
crystal-lize in the final liquid, including sylvite (potassium
chloride) This process produces concentrated
crys-talline layers that consist of only one or two major
minerals
World evaporite bodies can be divided into marine deposits, the thickest and most extensive in origin, and continental deposits Marine evaporites may form in marginal lagoons closed off from the sea by a sandbar or other barrier Another important environ-ment is the sabkha, a shallow margin of a sea or ocean
in an extremely arid climate, as occurs, for example,
in the Persian Gulf Continental deposits most com-monly form in temporary desert lakes called playas Evaporite minerals in playas are derived from streams that leach marine brines trapped in sedimentary rocks from surrounding mountains
Major evaporite localities in North America are the Michigan Basin (Salina deposits), the Permian Basin
of Texas and New Mexico, the Midcontinent field cen-tered in Kansas and adjacent states, and the borate de-posits of Death Valley and adjacent areas The first three of these localities are mostly known for halite and gypsum production They are primarily marine deposits formed in shallow continental seas during Si-lurian times (Michigan Basin) or during the Permian period (Permian Basin and Midcontinent) The Death Valley area is famous for its borate deposits, minerals that were deposited in playas
John L Berkley
See also: Borax; Boron; Carbonate minerals; Deserts; Gypsum; Limestone; Magnesium; Oceans; Salt; Salt domes; Sedimentary processes, rocks, and mineral deposits; Strontium; Water
Exclusive economic zones
Category: Government and resources Date: December 10, 1982
Although the concept of a conservation zone off na-tional coasts was not new, the exclusive economic zone (EEZ), created by the United Nations Convention on the Law of the Sea, was a legal and political achieve-ment because it was the result of a consensus by all the world’s states.
Background Part V of the United Nations Convention on the Law
of the Sea of December 10, 1982, established the ex-clusive economic zone of a coastal state as “an area be-yond and adjacent to the territorial sea” which is
un-Gypsum-selenite is one example of an evaporite (USGS)