Encyclopedia of Global Resources part 33 pot

Department of Energy Secretary of Energy Deputy Secretary Federal Energy Regulatory Commission Chief of Staff Office of the Under Secretary For Nuclear Security/ Administrator for Nation

290 • Department of Energy, U.S Global Resources

U.S Department of Energy

Secretary of Energy Deputy Secretary

Federal Energy

Regulatory

Commission

Chief of Staff

Office of the

Under Secretary

For Nuclear Security/

Administrator for

National Nuclear

Security Administration

Office of the Under Secretary

Office of the Under Secretary for Science

Associate Administrator for Management and Administration

Advanced Research Projects Agency-Energy

General Counsel

Chief Financial Officer

Chief Information Officer

Chief Human Capital Officer

Management

Public Affairs

Assistant Secretary for Congressional and Intergovernmental Affairs

Assistant Secretary for Policy and International Affairs

Health, Safety and Security

Inspector General

Economic Impact and Diversity

Hearing and Appeals

Intelligence and Counterintelligence

Developmental Staff and Support Offices

Energy Information Administration

Bonneville Power Administration

Southwestern Power Administration

Western Area Power Administration

Deputy Administrator

for Defense Programs

Deputy Administrator

for Defense Nuclear

Nonproliferation

Deputy Administrator

for Naval Reactors

Deputy Under Secretary

for Counterterrorism

Associate Administrator

for Defense Nuclear

Security

Associate Administrator

for Emergency

Operations

Associate Administrator

for Infrastructure

and Environment

Associate Administrator

for Management

and Administration

Assistant Secretary for Energy Efficiency and Renewable Energy Assistant Secretary for Environmental Management Assistant Secretary for Fossil Energy Assistant Secretary for Nuclear Energy Assistant Secretary for Electricity Delivery and Energy Reliability Civilian Radioactive Waste Management

Legacy Management

Office of Science

Advance Scientific Computing Research

Basic Energy Sciences

Biological and Environmental Research

Fusion Energy Science

High Energy Physics

Nuclear Physics

Workforce Development for Teachers and Scientists

Southeastern Power Administration

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

Accelera-tor LaboraAccelera-tory, SLAC National AcceleraAccelera-tor

Labora-tory, and other national laboratories During the Bill

Clinton administration, the Department of Energy

proposed numerous regulations for disposal of

haz-ardous wastes (such as plutonium) Under the free

market ideology of President George W Bush, the

De-partment of Energy promoted extraction of oil and

nonrenewable energy resources from federal lands in

the West and in Alaska

Howard Bromberg

Web Site

U.S Department of Energy

http://www.energy.gov/

See also: American Mining Congress; American

Pe-troleum Institute; Atomic Energy Acts; Atomic

En-ergy Commission; Biofuels; Biotechnology;

Depart-ment of Agriculture, U.S.; DepartDepart-ment of the Interior,

U.S.; Department of Transportation, U.S.; Energy

economics; Energy politics; Energy storage; Gasoline

and other petroleum fuels; Manufacturing, energy

use in; Nuclear Energy Institute; Oil embargo and

en-ergy crises of 1973 and 1979; Organization of Arab

Pe-troleum Exporting Countries; Organization of

Petro-leum Exporting Countries; Solar energy

Department of the Interior, U.S.

Category: Organizations, agencies, and programs

Date: Established 1849

The U.S Department of the Interior is the federal

agency entrusted with conserving much of the nation’s

natural resources These resources include federal

for-ests and grazing land; national parks; water and

irri-gation; oil, gas, and coal; American Indian lands;

and fish and wildlife.

Background

The Department of the Interior is part of the

execu-tive branch of the U.S government The secretary of

the interior is a member of the president’s cabinet,

confirmed by the Senate The three original execu-tive departments of the federal government estab-lished in 1789 were Foreign Affairs, War, and Trea-sury Given the limited role intended for the federal government in internal affairs, there was no executive department to handle general domestic management

As the range of federal responsibilities emerged, Con-gress established the Department of the Interior on March 3, 1849, to assume various domestic duties of the federal government

Impact on Resource Use

In the second half of the nineteenth century, the De-partment of the Interior conducted a wide range of domestic activities, such as controlling American In-dian affairs, managing federal lands, paying federal pensions, granting patents, conducting the census, constructing the infrastructure for the District of Co-lumbia, surveying the Western territories, and over-seeing federal monetary and land grants to hospitals and colleges As a result, the Department of the Inte-rior received the unofficial title of “Department of Ev-erything Else.” As Congress created additional de-partments to assume these manifold tasks, the chief purpose of the Department of the Interior came into view: to manage and conserve the natural resources of the nation

The principal work of the modern Department of the Interior is performed by eight bureaus Perhaps the best way to understand the crucial role the De-partment of the Interior plays in administering the nation’s resources is to outline the functions of its ma-jor divisions The Bureau of Land Management man-ages more than 100 million hectares of federal lands, much of which is leased for cattle grazing and ranch-ing, lumber loggranch-ing, coal and mineral minranch-ing, and oil and gas drilling These leases raise as much as $23 bil-lion annually for the federal government and account for about 30 percent of the nation’s energy produc-tion The National Park Service manages 33 million hectares, comprising 391 federal parks, monuments, and cultural sites The Fish and Wildlife Service man-ages about 40 million hectares of wildlife refuges to conserve and foster marine and animal life The Bu-reau of Indian Affairs manages 27 million hectares of American Indian tribal and reservation lands The Bureau of Reclamation manages 479 dams and 348 reservoirs, which provide water to much of the West The U.S Geological Survey conducts geological and topographical research

In total, the Department of the Interior plays a

cru-cial role in conserving federal lands, forests, and parks;

irrigating and supplying fresh water; protecting

ma-rine and land wildlife; and leasing lands for material,

mineral, and energy production With jurisdiction

over such a wealth of resources, the Department of the

Interior has been prone to scandal In 1929,

Depart-ment of the Interior secretary Albert Falls was

con-victed of bribery in the Teapot Dome scandal In the

administration of President George W Bush, Depart-ment of the Interior officials often seemed ambiva-lent about the natural treasures that they were obliged

to protect In a December, 2008, report, Department

of the Interior inspector general Earl Devaney found unethical, wasteful, and corrupt behavior in the Min-erals Management Service and other divisions of the Bush administration’s Department of the Interior

Howard Bromberg

U.S Department of the Interior

SECRETARY

DEPUTY SECRETARY

INSPECTOR GENERAL SOLICITOR

NATIONAL BUSINESS CENTER

NATIONAL

PARK

SERVICE

OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT

U.S FISH AND WILDLIFE SERVICE

MINERALS MANAGEMENT SERVICE

BUREAU

OF INDIAN AFFAIRS

U.S.

GEOLOGICAL SURVEY

BUREAU

OF LAND MANAGEMENT

BUREAU OF RECLAMATION

ASSISTANT SECRETARY POLICY, MANAGEMENT,

AND BUDGET AND CHIEF FINANCIAL OFFICER

ASSISTANT SECRETARY

FISH AND WILDLIFE

AND PARKS

ASSISTANT SECRETARY WATER AND SCIENCE ASSISTANT SECRETARY

LAND AND MINERALS MANAGEMENT

ASSISTANT SECRETARY INDIAN AFFAIRS

OFFICE OF SPECIAL TRUSTEE FOR AMERICAN INDIANS

Web Site

U.S Department of the Interior

http://www.doi.gov/

See also: Bureau of Land Management, U.S.; Bureau

of Mines, U.S.; Bureau of Reclamation, U.S.;

Depart-ment of Agriculture, U.S.; DepartDepart-ment of Energy,

U.S.; Department of Transportation, U.S.; Forest

Ser-vice, U.S.; National Park Service; National Parks Act,

Canadian; Public lands; U.S Geological Survey

Department of Transportation, U.S.

Category: Organizations, agencies, and programs

Date: Established 1966

The Department of Transportation works to provide

ef-ficient, economic, safe, and environmentally sound

national transportation systems on land, in the air,

over U.S waters, and through underground pipelines.

In this role, it regulates the transport of resources

throughout the country It is one of the departments of

the federal government that reports directly to the

presi-dent of the United States.

Background

On March 2, 1966, President Lyndon B Johnson

pro-posed the structure for a new executive department

pertaining to federal aspects of transportation On

October 15, 1966, Congress established the

Depart-ment of Transportation More than thirty existing

agencies with some ninety thousand employees were

brought together in creating the Department of

Trans-portation

Impact on Resource Use

The transportation systems of the nation are intricately

linked to the resources of the nation and the world

Most physical resources—anything from timber to

gasoline to crushed stone—are transported from

pro-ducer to consumer through parts of the national

trans-portation system The transtrans-portation industry is itself

a major consumer of many resources, and the

Depart-ment of Transportation assists in efforts to reduce

pol-lution and destruction of natural ecosystems and to

in-crease the efficiency of the industry’s use of resources

Environmental issues that are researched through

funding from the Department of Transportation

in-clude the safe packaging and transportation of haz-ardous materials and the effects of airline and auto-mobile emissions on air quality Also studied are the water quality in rivers and oceans (particularly as af-fected by merchant shipping and inland barge trans-portation) and how best to preserve wetlands or wild-life habitats during the construction of highways, airports, and urban transit systems The Department

of Transportation conducts research on the feasibility

of electric transportation regarding both automobiles and mass transit

The department is the main force in the federal government for developing and coordinating a na-tional transportation system and developing a nana-tional policy regarding transportation Its responsibilities include the development and enforcement of trans-portation safety improvements, the development of international transportation agreements, and the smooth running of accessible transportation for the general public It coordinates transportation issues with states and cities and provides technical assistance

to other levels of government The department ac-quires equipment and services and disburses federal funding to state and municipal authorities for trans-portation purposes

The Department of Transportation has a number

of operating divisions Each is headed by an adminis-trator who answers directly to the secretary of the De-partment of Transportation, who heads the depart-ment and serves on the president’s cabinet The divisions are the Federal Motor Carrier Safety Admin-istration, Federal Railroad AdminAdmin-istration, Federal Transit Administration, the Pipeline and Hazardous Materials Safety Administration, the Surface Trans-portation Board, the Federal Aviation Administra-tion, the Federal Highway AdministraAdministra-tion, the Saint Lawrence Seaway Development Corporation, the Na-tional Highway Traffic Safety Administration, the Maritime Administration, and the Research and Spe-cial Programs Administration

In 2003, the Department of Transportation under-went a slight restructuring when two of its divisions, the United States Coast Guard and the Transporta-tion Security AdministraTransporta-tion, became parts of the De-partment of Homeland Security Each of the eleven divisions is involved in specific aspects of resource and environmental management The National Highway Traffic Safety Administration, for example, assists in the development and enforcement of national fuel economy standards The Federal Aviation

tration assists in studies related to changes in the

ozone layer as a result of airline emissions

Dion C Stewart

Web Site

U.S Department of Transportation

http://www.dot.gov/new/index.htm

See also: National Oceanic and Atmospheric

Admin-istration; Transportation, energy use in

Desalination plants and technology

Category: Obtaining and using resources

Seawater and other salt-containing waters are

con-verted into potable water by distillation, reverse

osmo-sis, and other processes experimentally, and

increas-ingly practically, in regions where water resources are

limited or expensive.

Background

For many years, large ships at sea have used

distilla-tion processes to convert seawater into usable water

for passengers and crews because it is more

economi-cal than carrying enormous quantities of fresh water

for drinking, cooking, and cleaning In desert regions

and some areas that have limited suitable fresh water

available, distillation and, more recently, membrane

processes have been introduced for the conversion of

brackish water, industrial effluents, wastewater, and

seawater Large-scale pilot processes have been rare

One notable example is a plant that was built in San

Diego in the 1950’s and later shipped to the U.S naval

base at Guantánamo Bay in Cuba It can produce

13 million liters of distilled water per day

Because brackish water and various wastewaters

contain between 500 and 5,000 parts per million of

dissolved solids, and seawater and geothermally

pro-duced brines contain up to 50,000 or more, a number

of different processing methods have been

devel-oped In addition, the end use of the water may

dic-tate the superiority of one method above the others

For many agricultural purposes, water containing a

few thousand parts per million can be used, whereas

U.S drinking water standards are set at a maximum of

500 (in actuality, many U.S cities’ water supplies

ex-ceed this standard)

Distillation Methods Distillation methods were first described by Aristotle, but they had their first practical use aboard English naval vessels in the 1600’s Since then they have be-come much more complex, but they still involve a high-cost, energy-intensive boiling process, and sub-sequently a cooling process for liquefaction of the steam generated The original processes required submerged tubes, which became encrusted with chemical deposits Multistage flash process plants are currently used in which the latent heat of evaporation

of the water is captured and reused, and the scaling is diminished by adding chemicals or removing the ions causing the deposits Newer variations of these pro-cesses are being investigated Some attempts have been made to couple power generation plants with distillation units, which may provide more desirable economy of operation

Various versions of the multistage flash process are used in many parts of the Middle East and in more than three-quarters of the currently operating sys-tems Other designs for distillation plants have been proposed, and some have been built Most of these have used horizontal tube processes with a design that permits multiple stages with vacuum distillation and a gradual reduction of saline content by incorporating steam with the brine Large installations are currently incorporating this design Smaller plants have em-ployed a vapor compression procedure for industrial plants and resort hotels, but these are gradually being replaced by reverse osmosis facilities

Solar distillation procedures would appear to offer great future alternatives in the very regions where water is in short supply If solar energy could be more cheaply and efficiently obtained, and the land area needed made available, the saline water conversion problem would be solved relatively easily

Membrane Methods Although reverse osmosis has been most heavily pro-moted, there is actually a large group of related proce-dures that utilize membrane separations to purify water In ordinary osmosis, such as occurs through cell walls, a semipermeable membrane (one through which only the solvent can flow) allows water to flow from a less concentrated solution into a more concen-trated one (thus exhibiting an “osmotic pressure”) In reverse osmosis, pressure is exerted on the more con-centrated solution, overcoming the osmotic pressure and reversing the flow After the brine (saline water)

has been concentrated in this manner, the process is

repeated with fresh brine

Among the membranes that have been utilized,

most are polyamides and polyimides, which closely

re-semble protein structures Reverse osmosis has been

most effective with brackish waters, which do not have

the high osmotic pressure of seawater to overcome

However, improved membrane systems have

permit-ted construction of larger seawater charged reverse

osmosis plants in the 13-million-liters-a-day range A

procedure known as electrodialysis permits an

elec-tric field to assist in directing ion flow through

mem-branes, which are permeable to either cations or

an-ions; some success in using this method with brackish

water has been achieved Pressurization cycles with

ion exchange resins or membranes have been

success-ful with low energy requirements, but experiments

have failed to find the high-strength materials

re-quired to survive the high pressures needed

Ion Exchange Methods

Utilizing ion exchange resins in a normal flow-by

mode is very reasonable for purifying slightly brackish

water In fact, it is used to soften water in many

com-munities with hard-water supplies Resins that replace

metallic ions with positive hydrogen ions, and

non-metal ions with negative hydroxide ions, can readily

accomplish that limited task, but they are not

ade-quate for seawater conversion The necessity of

regen-erating the exhausted resins with acid or base make

designing a continuous process more difficult

Freezing and Solvent Extraction Methods

When a solution freezes under equilibrium

condi-tions, the solid formed is pure solvent Therefore,

when an iceberg forms, it contains very pure water It

has been proposed that icebergs could be towed to

water-short regions However, mechanical problems,

such as providing appropriate freezing chambers and

removing brine from the ice surface have prevented

these methods from being seriously explored Solvent

extraction procedures have been tried

experimen-tally, but solvent use and removal are costly

William J Wasserman

Further Reading

Khan, Arshad Hassan Desalination Processes and

Multi-stage Flash Distillation Practice New York: Elsevier,

1986

Lauer, William C., ed Desalination of Seawater and

Brackish Water Denver, Colo.: American Water

Works Association, 2006

National Research Council of the National

Acad-emies Desalination: A National Perspective

Washing-ton, D.C.: National Academies Press, 2008

Simon, Paul Tapped Out: The Coming World Crisis in

Water and What We Can Do About It New York:

Wel-come Rain, 1998

Spiegler, K S., and A D K Laird, eds Principles of

De-salination 2d ed New York: Academic Press, 1980.

Web Site National Academies Press Desalination: A National Perspective http://books.nap.edu/

openbook.php?record_id=12184&page=R1 See also: Oceans; Salt; Solar energy; Water

Desertification

Category: Geological processes and formations

Desertification is the degradation of semiarid lands and includes the reduction in the biological diversity of the ecosystem, the reduction in soil nutrients, and soil erosion.

Background Desertification occurs over a period of years, with nu-merous factors interacting to stress the environment Desertification results when social, political, and eco-nomic forces cause agricultural exploitation beyond the carrying capacity of marginal arid lands Airborne and waterborne erosion strip vulnerable topsoil, ren-dering the land less productive over time People liv-ing in areas undergoliv-ing desertification have poor harvests and are increasingly unable to feed them-selves

Although desertification can result from natural causes over eons, it can occur in relatively short pe-riods of time, notably as a result of improper land-use management—usually a combination of defor-estation and overgrazing on semiarid grasslands Nonnative cash crops and monoculture plantations quickly deplete soils, impoverishing the ecosystem and accelerating desertification In developed coun-tries, boom and bust agricultural practices in arid

lands cause overexpansion during favorable climatic

conditions, followed by drought People living on

marginal lands in less developed countries depend on

subsistence agricultural production Drought causes

these people severe hardships, as their crops fail and

animal herds die Sustainable development of

semi-arid lands in less developed countries would benefit

many impoverished people worldwide

Desertification in the Western Hemisphere

In 1806, Zebulon Pike characterized the southern

plains as a sandy wasteland, an area later called the

“Great American Desert” on maps Following the

Homestead Act of 1862, 65 hectares of shortgrass

could be claimed by settlers living and working on the

land, and some people thought that to be sufficient

incentive to migrate there Amish and Mennonite

set-tlers found the 65 hectares sufficient for their type

of agriculture, but the concept of large commercial

ranches and farms, coupled with the introduction of

machinery, prompted the passage of the Enlarged

Homestead Act of 1909, resulting in a land rush

By the time World War I began, wheat was the

fa-vored crop in the Great Plains Previously

unculti-vated land throughout Kansas, Colorado, New

Mex-ico, Oklahoma, and Texas was plowed and planted

with wheat by residents and absentee

farmer-specula-tors between the end of World War I and 1930 When

a lengthy drought began in 1931, precipitation was

spotty, and wheat crops began failing Fields were

abandoned, and the airborne soil erosion which

char-acterized the Dust Bowl began

Within the United States, elimination of

home-steading, massive purchase of marginal land, large

public works projects, and agricultural subsidies

helped reclaim marginal desert lands throughout the

Great Plains and Southwest The “New Deal” of

Presi-dent Franklin Delano Roosevelt began land

reclama-tion using the Soil Conservareclama-tion Service and the

Civil-ian Conservation Corps throughout the Dust Bowl

region, sowing sorghum and planting shelterbelts of

trees in an effort to limit soil erosion The

introduc-tion of contour plowing limited some of the worst

disk-plowing problems for agriculture

The Sahel: Southern Encroachment of the

Saharan Desert

The African region known as the Sahel, which

roughly follows the 15° north parallel, is an example

of dry woodland and dry wooded grassland

undergo-ing desertification Its northern border with the Sa-hara Desert receives 150 millimeters of annual rain-fall; its southern border receives 600 millimeters of rain yearly

Between 1931 and 1960 the Sahel experienced greater than normal levels of precipitation, coupled with a doubling in population During this time, a large part of the Sahel was populated by nomadic peo-ples herding small livestock flocks and practicing sub-sistence agriculture In 1970, a period of decades-long drought began This drought signaled a period of overgrazing by livestock and deforestation to feed cooking fires, two key factors in accelerating desertifi-cation Starting in 1968, the Sahel began to move southward from its 1931-1960 boundaries Warmer ocean waters changed rainfall patterns, resulting in less precipitation in the northern Sahel in the late twentieth century More than 60 percent of foreign aid in the region was expended on road construction, which consumed valuable water resources Develop-ment of large-scale dams in the Senegal River Valley during the 1980’s caused population displacement because much of the irrigated land was taken over by large plantations growing cash crops of peanuts, rice, and cotton Deforestation to expand plantations was widespread in Senegal

Annual rainfall began to increase in the mid-1990’s Satellite data show that vegetative growth in the Sahel increased beyond what would be expected from observed rainfall In Niger, where felling of nitrogen-fixing gao acacia trees has stopped, an estimated 49,000 square kilometers of savanna showed in-creased vegetation by 2008

In 2008, the population of the Sahel was estimated

at fifty million Emigration via the port of Dakar to Eu-rope, or overland to North Africa, continues to re-duce the population, as does continuing warfare in the Darfur region of Sudan, which claimed an esti-mated 200,000 lives between 2003 and 2008 Defores-tation has been rapid around Darfur refugee camps,

as trees have been cut to fuel refugee cooking fires and brick kilns for houses for United Nations aid workers

Mitigation of Desertification Identification of the problems caused by desertifica-tion by nadesertifica-tional governments and internadesertifica-tional agen-cies led to concerted efforts to halt and reverse the process during the late twentieth and early twenty-first centuries Developed nations, including the

United States and Australia, have relied heavily on

technology to combat desertification Ranchers have

formed effective organizations to lobby the central

governments for aid Drilling wells, building dams,

in-stalling irrigation canals, using chemical fertilizers on

depleted soil, using crop-dusting airplanes to limit

pest damage, and implementing large-scale reforesta-tion and revegetareforesta-tion programs are some of the meth-ods used to combat desertification

In Australia, ranchers of large areas import feed in drought years and move herds of cattle and sheep out

of desert environments to more productive grazing

Equator

Tropic of Cancer

Tropic of Capricorn

Gulf of Guinea

M e d i t e r r a n e a n S e a

A t l a n t i c

O c e a n

I n d i a n

O c e a n

True desert

Acute risk of

desertification

Moderate to

great risk

Desertification of Africa

land Government-sponsored selective breeding

pro-grams produced special cattle breeds—the Belmont

Red and the Australian Milking Zebu—better suited

to production in arid lands

Less developed countries rarely have the resources

to purchase technology International aid efforts

fo-cused on building dams have been found to result in

dislocation of hundreds of thousands of people while

worsening public health problems like

schistosomia-sis and malaria Because of these problems, beginning

in the 1990’s, international aid organizations

increas-ingly emphasized the need for introducing low

tech-nology to combat desertification and permit

sustain-able development Important initial steps included

involvement of the local populace to establish

sustain-able land-use policies and then to teach agricultural

techniques to reclaim land Natural revegetation, the

self-seeding by plants remaining in the area, is

encour-aged, as is the use of direct seeding of crops and

plant-ing of trees to limit erosion Where overgrazplant-ing by

livestock is removing most of the sparse natural

vege-tative covering, reducing and limiting herd size is

im-portant Concentration of landownership accelerates

growth of unsustainably large herds and encourages

overgrazing Farmers at the subsistence level own few

animals, using them mainly for milk production

Minimizing the use of wood for cooking fuel

through the introduction of more efficient cooking

stoves and solar cookers has lessened desertification

in the Sahel Other successful low-technology

meth-ods include digging shallow basins for planting in

eastern Mali and stone line construction to retain

water and limit erosion in Burkina Faso In 1984, after

stone lines were completed in Yatenga Province in

Burkina Faso, crop yields doubled

In less developed countries where a few

landown-ers control large, semiarid plantations utilized for

nonsustainable cash crops, such as peanuts and

cot-ton, land redistribution to smaller, privately owned

farms growing drought-resistant crops for local

con-sumption is ideal However, the World Bank

under-went a paradigm shift in the 1980’s that favored

com-mercial farmers over small farmers This accelerated

desertification in many arid regions of less developed

countries, especially in Africa Large farmers raise

un-sustainable large herds and force poor people onto

marginal land

Mitigation of desertification becomes difficult when severe periodic droughts occur Expansion of agri-culture above subsistence levels is inevitable during good times when crop yields increase When drought struck the U.S Great Plains from 1954 to 1957 and again from 1974 to 1977, airborne erosion identical to the 1930’s Dust Bowl occurred, with dramatic eco-nomic consequences Deep-well irrigation was intro-duced, lessening the apparent risks of large-scale monocrop agriculture in the region Technology has become essential to maintaining agriculture in the Great Plains

Anita Baker-Blocker

Further Reading Hazell, Peter, and Stanley Wood “Drivers of Change

in Global Agriculture.” Philosophical Transactions of

the Royal Society of London 363, no 1491 (February

12, 2008): 495-515

Liebesman, Lawrence R., and Rafe Petersen

Endan-gered Species Deskbook Washington, D.C.:

Environ-mental Law Institute, 2003

Worster, Donald Dust Bowl: The Southern Plains in the

1930’s 25th anniversary ed New York: Oxford

Uni-versity Press, 2004

Web Sites Environment Canada: Canadian Wildlife Service

Species at Risk http://www.cws-scf.ec.gc.ca/

theme.cfm?lang=e&category=12 NOAA Fisheries Service: Office of Protected Resources

Endangered Species Act http://www.nmfs.noaa.gov/pr/laws/esa U.S Fish and Wildlife Service Endangered Species Program http://www.fws.gov/endangered See also: Climate and resources; Deserts; Drought; Erosion and erosion control; Food shortages; Irriga-tion; Overgrazing; Soil management; United Nations Convention to Combat Desertification; World Bank

Category: Ecological resources

Deserts are regions defined by the scarcity of a crucial

resource, water They are unique ecosystems with their

own types of plant and animal life; a number of desert

plants have been used by humans for thousands of

years Mining for minerals and petroleum also occurs

in desert regions around the world.

Background

Although deserts are characterized by general aridity,

there is no universal definition of a desert Webster’s

dictionary defines a desert as an “arid land with

usu-ally sparse vegetation; especiusu-ally such land having a

very warm climate and receiving less than 25

centime-ters of sporadic rainfall annually.” Deserts are

gener-ally thought of as hot and dry, but heat is not

necessar-ily a requisite of most definitions of a desert Low

precipitation does not, alone, characterize a desert

Arctic tundra landscapes often receive scant

precipi-tation, yet tundra soils are often saturated from low

evaporation and restrictive permafrost below a nar-row active thawed layer during the summer The com-mon perception of a desert is a trackless expanse of sand such as the Sahara or the Arabian Desert In real-ity, however, deserts are often fairly well vegetated The characteristic that all deserts have in common is aridity Aridity refers to a general dryness, not to short drought periods

Characteristics of Deserts Deserts are located on all continents; Antarctica is considered a desert They occur on a variety of sub-strates but often are characterized by historical ero-sion patterns leaving alluvial fans on the foothills of small mountains or hills and isolated islands of more resistant material These remnants are called buttes in the western United States Sandy soils are common, but wind-blown soils and ash deposits from volcanoes are also prevalent in many deserts Desert soils often lack structural aggregation and are subject to erosion They often have surface crusts from raindrop impact and deposits from sediments that are left as water infil-trates into the soil

Camels are led through the Sahara Desert, the largest hot desert on the planet (Fei Xuan/Xinhua/Landov)