Environmental Encyclopedia

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Environmental Encyclopedia 3

Organochloride

Production of biogas is another use of organic waste.

Biogas is used as an alternative energy source in some

third

world

countries. It is produced in digester units by the

anaerobic decomposition

of organic wastes such as ma-

nures and crop residues. Beneficial byproducts of biogas

production include sludges that can be used to fertilize and

improve soil, and the inactivation of pathogens in the waste.

In addition, there is ongoing research on using organic wastes

in developing countries: (1) in fish farming; (2) to produce

algae for human and animal consumption, fertilizer, and

other uses; and (3) to produce aquatic macrophytes for ani-

mal feed supplements.

[Teresa C. Donkin]

ESOURCES

OOKS

Polprasert, C. Organic Waste Recycling. New York: Wiley, 1989.

ERIODICALS

Logsdon, G. “Composting Industrial Waste Solves Disposal Problems.”

Biocycle 29 (May-June 1988): 48–51.

Organization of Petroleum Exporting

Countries

Established in 1960 by Iran, Iraq, Kuwait, and Venezuela,

the Organization of

Petroleum

Exporting Countries

(OPEC) was created to control the price of oil by controlling

the volume of production. Modeled on the Texas Railroad

Commission in the United States, the group was also in-

tended to make other decisions about petroleum policy and

to provide technical and economic support to its members.

Indonesia, Libya, Qatar, Algeria, Nigeria, Saudi Arabia, and

the United Arab Emirates have been admitted since 1960,

and it is now estimated that the nations in OPEC control

nearly three-quarters of the world’s oil reserves.

In October 1973, members of OPEC met at their

headquarters in Vienna and voted to raise oil prices by 70%.

OPEC is dominated by oil-producing countries from the

Middle East, and this decision was designed to retaliate

against Western support of Israel during its war with Egypt.

At a conference in Tehran, Iran, in December of that same

year, OPEC countries raised oil prices an additional 130%,

and they enacted an embargo on shipments to the United

States and the Netherlands. The Iranian revolution in 1979

further restricted the world supply of oil, intensifying the

effects of OPEC policies; between 1973 and 1980, the price

of a barrel of oil rose from three dollars to 35 dollars.

The steep rise in oil prices had a disruptive effect in

the United States, which is the largest oil importer in the

world. It had an ever greater economic impact on industrial-

1037

ized countries such as Japan, which have little or no petro-

leum reserves of their own. But the economies in

less devel-

oped countries

(LDC) were the hardest hit; the rising price

of oil decreased their purchasing power, increasing their

trade deficit as well as their level of debt. There was a rapid

transfer of wealth to oil-producing countries during this

period, with the annual income of OPEC countries increas-

ing 22.5 billion dollars in 1973 to 275 billion dollars in 1980.

The organization was not, however, able to maintain

its influence over the international oil market in the 1980s,

and prices dropped to as low as 10 dollars a barrel during

this decade. World oil consumption reached a peak in 1979,

at a high of 66 million barrels a day, and then dropped

sharply in the years that followed. Many Western countries

were encouraging

conservation

; they had also invested in

other sources of energy, most notably

nuclear power

. Oil

exploration had resulted in discoveries in Alaska and the

North Sea; Mexico and Soviet Union, oil-exporting coun-

tries that were not members of OPEC, had also become an

increasingly important part of the international petroleum

trade. As their power over the price of oil became more

diffused, consensus within OPEC became more difficult,

and these internal divisions were made worse by political

conflicts within the Middle East, particularly the war be-

tween Iran and Iraq.

From an environmental perspective, the most impor-

tant effect of the oil price shocks of the 1970s may have

been how it changed world patterns of energy consumption.

Though the increase in prices forced many countries to use

coal

and nuclear power despite the damage they can do

to the

environment

, economic pressures also stimulated

research into many

alternative energy sources

, such as

solar energy

wind energy

, and hydroelectric power. In

the last decade of the twentieth century, the sudden decrease

in oil prices limited the sense of urgency as well as the

funding for many of these research projects, and some envi-

ronmentalists have suggested that higher oil prices might

be better for the environment and the global economy over

the long term.

[Douglas Smith]

ESOURCES

RGANIZATIONS

Organization of Petroleum Exporting Countries, Obere Donaustrasse 93,

Vienna, Austria A-1020 + 43-1-21112 279, Fax: + 43-1-2149827, <http://

www.opec.org>

Organochloride

Usually refers to organochlorine pesticides, although it could

also refer to any chlorinated organic compound. The organo-

Environmental Encyclopedia 3

Organophosphate

chlorine pesticides can be classified by their molecular struc-

tures. The cyclopentadiene pesticides are aliphatic, cyclic

structures made from Diels-Alder reactions of pentachloro-

cyclopentadiene, and include

chlordane

, nonachlor, hepta-

chlor, heptachlor epoxide, dieldrin, aldrin, endrin,

mirex

and

kepone

. Other subclasses of organochlorine pesticides

are the DDT family and the hexachlorocyclohexane isomers.

All of these pesticides have low solubilities and volatilities

and are resistant to breakdown processes in the

environ-

ment

. Their toxicities and environmental persistence have

led to their restriction or suspension for most uses in the

United States. See also Organophosphate

Organophosphate

Refers to classes of organic compounds that are often used in

insecticides. Many of the organophosphate pesticides were

developed over the last 30 years to replace organochlorine in-

secticides. They generally have the highest solubilities and

shortest half-lives of the common classes of pesticides, but

tend to have higher acute toxicities. Organophosphates act by

disrupting the central nervous system, specifically by blocking

the action of the

enzyme

acetylcholinesterase, which controls

nerve impulse transmission. Organophosphates can impact

human health at moderate levels of exposure, causing disori-

entation, numbness, and tremors. Acute exposures can cause

blindness and death. Well-known organophosphate pesti-

cides include parathion, malathion,

diazinon

, and phosdrin.

See also Cholinesterase inhibitor; Organochloride

David W. Orr (1944 – )

American environmental writer

In recent years, an effort has been undertaken to make every

citizen numerate, that is, able to use mathematics at a level

that is minimally functional in modern society. David Orr,

and writers and thinkers of kindred mind, believe that for

citizens to be minimally functional in the complex, interde-

pendent world of the twenty-first century, they must go

beyond literacy in language and beyond numeracy and attain

also a certain level of ecological literacy.

Orr is best known for his 1992 book titled Ecological

Literacy and for his brief editorial essays in the journal Conser-

vation Biology, written from his position as education editor

for that journal. Born in Des Moines, Iowa, and raised in New

Wilmington, Pennsylvania, he holds degrees from Westmin-

ster College (BA), Michigan State University (MA), and the

University of Pennsylvania (Ph.D. in International Rela-

tions). He was a professor of political science before becoming

Professor and Chair of the Environmental Studies Program

at Oberlin College in Ohio. He is well-known for his criticism

1038

of the

environmental degradation

brought about by the

free market system, his critique of the American educational

system, and his activist attempts to change both systems to-

ward more ecologically sustainable behavior.

Though the free market system seems to be in the

ascendancy today, Orr believes that capitalism “is failing

because it produces too much and shares too little.” He

especially laments conservatives in the capitalist system who

do not understand the history and meaning of what conserva-

tive means. He claims that a genuine conservatism would

conservation

oriented and not intent, for example, on

perpetual economic growth that “has become the most radi-

calizing force for change in the modern world.”

Much of this failure in the western system he traces

to an ecological crisis that “represents, in large measure, a

failure of education.” He faults every level of education in

general for not teaching students how to learn, while in

school and throughout life, and for failing to define knowl-

edge adequately for postmodern life. Too many disciplines

do not consider the interrelations between people and the

earth on which they live. This failure, Orr claims, can “ulti-

mately...be traced to our schools and to our proudest univer-

sities.”

Much of Orr’s work focuses on changing universities,

to eliminate what he considers the nationwide campus em-

phasis on “fast knowledge,” or “ignorant knowledge” that is

“cut off from its ecological and social context.” He laments

the over-professionalization of the professorate, researchers

who churn out fast knowledge and create students (and

citizens) who are “knowledge technicians instead of broadly

thoughtful, liberally educated persons.” He relates nar-

rowness and self-interest to “the problem of ecological de-

nial,” in which people cannot think in the long term or about

the “large and messy questions” associated with environmen-

tal issues. Througout his career, Orr has received many

awards such as an Honorary Doctorate in Humane Let-

tersfrom Arkansas College in 1990 and the Benton Box

Award from Clemson University in 1995.

Orr believes that campus buildings even teach negative

lessons: “the design, construction, and operation of academic

buildings can be a liberal education in a microcosm that

includes virtually every discipline in the catalog.” Thus, he

has undertaken what is proving to be a life-long campaign

to change campuses to educational laboratories for ecological

systems and environmental sustainability.

[Gerald L. Young Ph.D.]

ESOURCES

OOKS

Orr, D. W. Ecological Literacy: Education and the Transition to a Postmodern

World. Albany: State University of New York Press, 1992.

Environmental Encyclopedia 3

Our Common Future

(Brundtland Report)

———. Earth in Mind: On Education, Environment, and the Human Pros-

pect. Washington, DC: Island Press, 1994.

Henry Fairfield Osborn (1887 – 1969)

American conservationist and naturalist

Born in Princeton, New Jersey, Osborn was the son of a

renowned paleontologist who was also president of the

American Museum of Natural History. Osborn graduated

from Princeton in 1909 and attended Cambridge University

in England. He then held a variety of jobs, working in freight

and railroad yards and serving as a soldier in World War I.

He finally took a position at a bank dealing in Wall Street

investments.

Throughout his life, Osborn had accompanied his fa-

ther on paleontological expeditions. As these trips continued

into his adulthood, Osborn realized that his true vocation

lay not finance but in natural science. In 1935 he accepted

a position as secretary of the New York Zoological Society,

an organization devoted to the “instruction and

recreation

of the people of New York.” He was named president of

the Society five years later and remained in office until 1968.

As president, he actively pursued the creation of the Marine

Aquarium at Coney Island, New Jersey, as well as improve-

ments to the Bronx Zoological Park.

Osborn recognized the crucial need for an organization

that would foster the preservation of

endangered species

and their habitats. With this purpose in mind, he founded

in 1947 the Conservation Foundation (CF), an adjunct of

the New York Zoological Society. CF was absorbed in 1990

by the

World Wildlife Fund

which still works for the conser-

vation of endangered

wildlife

and natural areas.

Osborn used his knowledge of

nature

and his posi-

tions within these organizations to influence policy in Wash-

ington. He served on the Conservation Advisory Committee

of the

U.S. Department of the Interior

as well as on the

Planning Committee of the Economic and Social Council

of the United Nations.

William Vogt

and later Paul R. Ehrlich, Osborn

often expressed concern about

population growth

and

available

natural resources

. He fully realized the serious

ramifications of environmental and ecological neglect and

understood the steps needed to conserve existing resources

and develop improved methods of distribution. He published

two highly successful books, Our Plundered Planet (1948)

and The Limits of the Earth (1953), each of which outlined

the importance of conservationist ideals and the perils of a

population explosion. Osborn was an active member of the

Save-the-Redwoods League

, International Council for

1039

Bird Preservation, and other related organizations. He died

in New York City in 1969 at the age of 82.

[Kimberley A. Peterson]

ESOURCES

OOKS

Osborn, Henry Fairfield. Cope: Master Naturalist. Salem, NH: Ayer, 1978.

———. Major Papers on Early Primates, Compiled From the Publications of

the American Museum of Natural History. New York: AMS Press, 1980.

———. Naturalist in the Bahamas: October 12, 1861–June 25, 1891. New

York: AMS Press, 1910.

———. Origin and Evolution of Life: On the Theory of Action, Reaction and

Interaction of Energy. Salem, NH: Ayer, 1980.

OSHA

see

Occupational Safety and Health

Administration

Otter

see

Sea otter

Our Common Future

(Brundtland

Report)

In late 1983

Gro Harlem Brundtland

, the former Prime

Minister of Norway, was asked by the Secretary-General

of the United Nations to establish and chair the World

Commission on

Environment

and Development, a special,

independent commission convened to formulate “a global

agenda for change.”

The Secretary-General’s request emerged from grow-

ing concern in the General Assembly about a number of

issues, including: long-term

sustainable development

; co-

operation between developed and developing nations; more

effective international management of environmental con-

cerns; the differing international perceptions of long-term

environmental issues; and strategies for protecting and en-

hancing the environment.

The commission worked for three years and produced

what is commonly known as “The Brundtland Report.” Pub-

lished in book form in 1987 as Our Common Future, the

report addresses what it identifies as “common concerns,”

such as a threatened future, sustainable development, and

the role of the international community. The report also

examines “common challenges,” including

population

growth

, food security,

biodiversity

, and energy choices, as

well as how to make industry more efficient. Finally, the

report lists “common endeavours,” such as managing the

commons, maintaining peace and security while not sus-

Environmental Encyclopedia 3

Overburden

pending development or degrading the environment, and

changing institutional and legal structures. A chapter on

each one of these concerns, challenges, and endeavors is

included in the book.

Two years after publication of the report, Brundtland

summarized its findings in a speech to the

National Acad-

emy of Sciences

in the United States. The reports’s core

concepts, she explained, were “that development must be

sustainable, and the environment and world economy are

totally, permanently intertwined.” She went on to assert that

these concepts “transcend nationality, culture, ideology, and

race.” She summarized by repeating the report’s urgent warn-

ing: “Present trends cannot continue. They must be re-

versed.”

The Brundtland Report issued a multitude of recom-

mendations to help attain sustainable development and to

address the problems posed by a global economy that is

intertwined with the environment. The report recommends

ways to deal with the debt crisis in developing nations, and

insists on linking poverty and environmental deterioration:

“A world in which poverty is endemic will always be prone

to ecological and other catastrophes.” The report also argues

that security issues should be defined in environmental rather

than military terms.

The members of the commission felt that a vast array

of institutional changes were necessary if progress was to be

made, and the report addresses these issues. It declares that

the problems confronting the world are all tied together,

“yet most of the institutions facing those challenges tend to

be independent, fragmented, working to relatively narrow

mandates with closed decision processes.” Much of the work

done by the commission focused on policy issues such as

long-term, multifaceted population policies and ways to cre-

ate effective incentive systems to encourage production, es-

pecially of food crops. Recommendations also include meth-

ods for a successful transition from

fossil fuels

to “low-

energy” paths based on renewable resources.

The report repeatedly notes the differences between

developed and developing nations in terms of energy use,

environmental degradation

, and urban growth, but it also

emphasizes that “specific measures must be located in a

wider context of effective [international] cooperation, if the

problems are to be solved.” The report always brings the

problems back to people, to the importance of meeting basic

human needs and the necessity of decreasing the disparities

between developed and developing countries: “All nations

will have a role to play in changing trends, and in righting

an international economic system that increases rather than

decreases inequality, that increases rather than decreases

numbers of poor and hungry.”

The report is not merely a grim listing of “ever increas-

ing environmental decay, poverty, and hardship in an ever

1040

more polluted world among ever decreasing resources.” Sur-

prising to some, it is also a documentation of “the possibilities

for a new era of economic growth,” an on-going era of

sustainable, non-destructive growth. See also Economic

growth and the environment; Environmental economics;

Environmental monitoring; Environmental policy; Environ-

mental stress; Green politics; International Geosphere-Bio-

sphere Programme; United Nations Earth Summit; United

Nations Environment Programme; World Bank

[Gerald L. Young Ph.D.]

ESOURCES

OOKS

Silver, C. S., and R. S. DeFries. One Earth One Future: Our Changing

Global Environment. Washington, DC: National Academy Press, 1990.

World Commission on Environment and Development. Our Common Fu-

ture. New York: Oxford University Press, 1987.

Overburden

Refers to the rock and

soil

above a desired economic re-

source, such as

coal

or an ore body. It is normally associated

with

surface mining

, in contrast to underground mining

where

tailings

are a more common byproduct. The depth

of overburden is a critical economic factor when assessing

the feasibility of mining. Unless the

topsoil

is stored for

later

reclamation

, overburden removal usually destroys this

crucial resource, greatly magnifying the task of natural or

cultural revegetation. In North America, overburden removal

requires blasting through hard caprock, which leave land-

scapes resembling fields of glacial debris. See also Mine

spoil waste

Overfishing

With the tremendous increase in the human population

since the industrial revolution, there has been an ever increas-

ing use and, often, exploitation of many of the world’s

natu-

ral resources

. The demand for fish and shellfish has exem-

plified this misuse of natural resources. Paralleling the

changes in agriculture, the fisheries industry has progressed

from a small-scale, subsistence operation to a highly mecha-

nized, ultra-efficient means of securing huge quantities of

fish and shellfish to satisfy the burgeoning market demand.

These industrialized commercial fisheries have allowed fish-

ermen to easily work the far offshore waters, and more

efficient refrigeration has allowed greater travel time, thus

allowing for longer excursions.

Overfishing results in the removal of a substantial

portion of a species’ population so that there are too few

Environmental Encyclopedia 3

Overfishing

individuals left to reproduce and bring the population back to

the level it was the year before. Overfishing has a tremendous

negative impact on nontarget

species

as well. More than

half, and occasionally as much as 90%, of a catch may be

discarded, and this can adversely affect the

environment

by altering predator-prey ratios and adding excess

organic

waste

through the dumping of nearly 30 million tons of

dead or dying fish and shellfish overboard annually. Over-

fishing has also negatively impacted diving seabird, sea turtle,

and dolphin populations since these animals often get

trapped and killed in fishing nets. It is estimated that 44,000

albatrosses are killed each year by Japanese tuna fishermen,

and that, over the years, tuna purse seine nets in the Eastern

Tropical Pacific have caused the death of millions of

dol-

phins

The offshore waters are not regulated as are the coastal

waters of our continents, therefore several populations of

commercially important species have been overfished. Often,

fishermen simply try to catch as many fish as possible (as

fast as possible), because they believe that any fish left in the

water will be caught by someone else. The codfish industry of

the Atlantic coast of Canada and the United States had

been a productive fishery since the time of the early settlers,

hundreds of years ago. But with the introduction, in 1954,

of a new kind of highly industrialized fishing vessel, the

factory trawler, conditions changed for the cod population.

In 1968, exceeding the normal catch for the region by over

500,000 tons, 810,000 tons of cod were taken off Labrador

and the Grand Banks off Newfoundland. In the decade to

follow, the cod population declined to the point that the

number of spawning codfish off Newfoundland in 1977

showed a 94% decrease from the number in 1962. Another

species to show population decline due to overfishing is the

American shad, often referred to as the poor man’s

salmon

Harvested by Native Americans and the early colonists, the

shad fishery was supplying one of the most commercially

valuable fish to the region surrounding the

Chesapeake

Bay

during the 1800’s. Overfishing, combined with an in-

crease in

pollution

and the disruption of spawning runs by

the damming of rivers, took a fishery with an annual harvest

of nearly 18 million pounds at the turn of the century to

less than 2 million pounds in the 1970s.

A tragic example of the effect of overfishing is seen

Georges Bank

in the Atlantic Ocean. Georges Bank,

discovered by the Italian explorer Giovanni da Verrazano in

the early part of the 16th century, was named after St.

George by English settlers in 1605. Home to over 100 species

of fish, Georges Bank has been a historically significant site

of plentiful fishing for centuries. It is an ovoid embankment

that is about 75 miles (120 km) off of the coast of New

England. It encompasses an area 149 miles (240 km) in

length and 75 miles (120 km) in width, and is over 330 feet

1041

(100 meters) above the sea floor of the adjacent Gulf of

Maine. A bank, or shoal, is a shallow portion of an ocean

that is analogous to a plateau. Georges Bank is part of a

large range of shoals that extends from Newfoundland to

the edge of the North American continental shelf. Georges

Bank itself is larger than the state of New Jersey, and is an

extremely important breeding ground for cod, haddo! ck,

herring, flounder, lobster, and scallops. Its unique conditions

are formed by the mingling of two major Atlantic currents:

the cold Labrador current and the warm Gulf stream. The

mixing of nutrient-rich and well-oxygenated waters in com-

bination with good light penetration due to shallow depth

creates an ideal environment for

plankton

that is a vital

food source for young fish.

Known for its abundant fish supply, Georges Bank

was heavily fished for centuries. Early fisheries believed the

supply to be inexhaustible. The first documented conse-

quence of indiscriminate fishing was in 1850 when, after a

concentrated season of overfishing, a dramatic decline in

halibut numbers in Georges Bank threatened commerce.

The near

extinction

of halibut in this area occurred when

ocean fishing was still accomplished using relatively small

sailboats and handlines with baited hooks. After World War

II, colossal factory-sized fishing ships were created and new

large-scale fishing techniques were employed in Georges

Bank. Miles of

gill nets

and other efficient methods became

standard tools for trolling the bank. Fisheries from the

United States, the Soviet Union, Spain, Japan, and Germany

collected huge bounties from Georges Bank for decades.

Each modern ship could catch as much cod in a single hour

as an average boat from the 1600s could collect in an enti!

re season. The fishing industry boomed from the 1950s

through the 1970s, until it became apparent that even the

ocean had limits that could be surpassed.

In 1976, the United States passed the Magnuson Act

which established American authority to ban international

factory fishing in the Georges Bank area. The intention was

to protect and preserve fish stocks for the United States and

Canada. Rather than initiate

conservation

strategies for

managing the fish populations of Georges Bank, western

fisheries free from foreign competition in the area, advanced.

The New England Council, created by the Magnuson Act

to protect Georges Bank, was effectively controlled by fishing

industry interests that did little to address growing concerns

about dwindling supplies.

In 1994 the National Marine Fisheries Service esti-

mated a 40% decline in cod stocks in the Georges Bank area

that occurred over an alarmingly short four-year period.

Survey after survey found that the once abundant bank had

been stripped of every prime commercial fish species that

once filled its waters. As a result, that same year, fishing

was banned in a 9,600 square kilometer area of Georges

Environmental Encyclopedia 3

Overgrazing

Bank. As of 1999, scientists reported that some commercial

species were beginning to show signs of a slow increase in

numbers, but that cod continued a rapid decline. While

the ban on heavy fishing continues, some strictly regulated

fishing is permitted in certain areas of Georges Bank. Al-

though the depletion of fish populations in Georges Bank

are assumed by some to be temporary, scientists remain

cautious about providing assurances of a return to former

abundance since recovery from such massive overfishing is

not well understood.

Because regions relatively close to land, such as

Georges Bank, tend to be more regulated, fishermen have

begun to move farther out into unregulated water. Lack of

regulations, however, is not the only reason fishermen are

going farther offshore. Many populations have been over-

fished in coastal waters, but fish and shellfish populations

have declined in these waters due to near-shore pollution as

well. Decreased

water quality

has had an impact on the

population numbers and also on the quality of the fish itself,

therefore creating a demand for fish and shellfish from dis-

tant, presumably cleaner, waters. Being driven farther off-

shore to make their catches, commercial fishermen may often

overfish a population to bring in more revenues to offset

their huge debt incurred on their equipment, crew, and ever

increasing fuel costs.

A particularly alarming new method of fishing that

threatens ocean

fauna

is cyanide fishing. Cyanide fishing

is an increasingly popular method of fishing that uses cyanide

to temporarily stun fish in exotic areas, like coral reefs. Once

stunned, the fish are easily collected, then sold either as

aquarium pets or as live fish in restaurants. Live fish sell for

much higher prices than frozen fish, and live fish selections

in restaurants is a growing trend. One problem with cyanide

fishing is that only about half of the fish captured survive

for sale, making it a wasteful effort. A second problem is

the nonselective

poisoning

of other

wildlife

found in the

ecosystems. Coral itself is killed by the cyanide used to flush-

out

exotic species

from hiding places for luxury fish markets

in Asia. Cyanide fishing constitutes a new threat for overfish-

ing. It is estimated that roughly 65 tons of cyanide are used

each year in Philippine coral reefs alone. Cyanide used on

one! area spreads and jeopardizes ocean life on a scale that

is poorly understood.

Popular trends in cuisine, in addition to live exotic

fish selections in restaurants, can effect fishing. During the

1980s, when a New Orleans chef popularized “blackened

redfish” and the dish was in demand across the country, the

Gulf of Mexico population of “redfish", actually the Red

drum, was nearly decimated by overfishing. Because of its

unpopularity as a food and game fish, the Red drum was

not regulated as are the more important commercial fish

and shellfish species of this region. Therefore, when orders

1042

for the fish started coming in from across the nation, com-

mercial fishermen began catching them in record numbers.

There were cases in which great numbers of dead redfish

were washing up on the shores of the Gulf states because

fishermen had caught too many to process on their vessels

and dumped the excess overboard. In just a couple of years

the Red drum population crashed in the Gulf of Mexico,

prompting the fish and game officials in all of the Gulf

states to halt

commercial fishing

for redfish. (A recovery

program, however, is meeting with success.) This problem

could have been avoided had the original dish been named

“blackened fish” or had the nation’s seafood markets and

restaurants known that the flavor in “blackened redfish” is

in the seasonings and not in the fish itself, thus relying on

local fisheries and the redfish of the Gulf of Mexico.

One means of offsetting overfishing by commercial

fishing fleets, and reducing fuel use as well, is

aquaculture

the cultivation and harvesting of fish and shellfish under

controlled conditions. With pressures on fish populations

from overfishing, increased pollution problems, and a dying

industry strapped with higher costs of fuel and equipment,

“fish farming” may offer a true alternative to greatly reduced

quantities and inferior quality seafood in the future. See also

Commercial fishing

[Eugene Beckham]

ESOURCES

ERIODICALS

Bricklemyer, E., S. Iudicello, and H. Hartmann. “Discarded Catch in

U.S. Commercial Marine Fisheries.” Audubon Wildlife Report. San Diego:

Academic Press, 1990–91.

Kunzig, Robert. 1995. Twilight of the Cod. Discover, April 1995,44–49,

52–57, 60.

Lawren, B. “Net Loss.” National Wildlife 30 (1992): 46–53.

Overgrazing

Overgrazing is one of the most critical environmental prob-

lems facing the western United States.

Rangelands

have

been mismanaged for over a hundred years, mainly due to

cattle grazing. In addition to consuming vegetation, cattle

alter the

ecosystem

of rangeland by tramping, urination,

defecation, and trashing. Degradation due to heavy livestock

grazing continues to occur in many diverse and fragile ecosys-

tems, including

savanna

desert

, meadow, and alpine com-

munities.

Riparian lands, highly vegetated, narrow strips of land

bordering rivers or other natural watercourses, make up only

two percent of rangelands, but have the most diverse popula-

tions of vegetation and

wildlife

. Overgrazing has had a

devastating effect on these areas. Cattle eat the seedlings of

Environmental Encyclopedia 3

Overhunting

young trees, which has led to the elimination of some

spe-

cies

, and this has reduced the species of birds in these areas

and disrupted migratory patterns. Lack of new tree growth

in riparian areas has also resulted in the drying up of stream

beds and the loss of

habitat

for fish and amphibians. It has

contributed to the problem of

soil erosion

desertification

and the

greenhouse effect

. Other rangeland ecosystems

are facing similar disruption.

The

Bureau of Land Management

(BLM) part of

the U. S. Department of the Interior is the largest landholder

in the United States. They are responsible for 334 million

acres of land which fall under multiple-use mandates. The

BLM leases much of this

public land

to individuals for

grazing purposes, charging ranchers approximately $1.35 per

month to graze one cow and a calf. It has been estimated

that the fair market value for such forage is $6.65, and the

agency has come under attack for leasing grazing rights at

extremely low rates. It has also been criticized for allowing

abusive land management practices. Critics claim that those

who utilize these public lands try to maximize profits by

putting excessive numbers of livestock on the range, and

they argue that almost half of the range areas in the United

States are in dire need of

conservation

Environmentalists argue that it is possible to eliminate

overgrazing and manage rangelands in a way that both pre-

serves ecosystems and meets the needs of ranchers. They

advocate above all the reduction of herds. They also suggest

that cattle should not be allowed to roam at will and should

be rotated among various pastures, so that all rangeland areas

can receive back-to-back spring and summer rest.

Perhaps the main obstacle in conservation of range-

lands is the lack of knowledge regarding their diverse ecosys-

tems. Rangelands are regions where natural revegetation

tends to be slow. Artificial attempts to introduce and estab-

lish plant growth have been frustrated by the fact that devel-

opment is a long-term process in these environments as

well as by other factors. Knowledge of the dynamics of

competition

, reaction, and stabilization of species is mini-

mal. For over a century, rangers have tried to eliminate

sagebrush, planting wheatgrass in its place. The solution

has been short-lived because sagebrush usually prevails over

wheatgrass in the natural

succession

of plants. To further

compound the problem, overgrazing has depleted the peren-

nial grasses that compete with sagebrush, and the plant has

become even more prolific. A better understanding of the

dynamic relationship between plants, animals,

microorgan-

isms

, soil, and the

climate

is necessary to reestablish range-

land areas. See also Agricultural pollution; Agricultural Stabi-

lization and Conservation Services; Agroecology; Feedlot

runoff; Feedlots; Land use; Sagebrush Rebellion; Taylor

Grazing Act (1934)

[Debra Glidden]

1043

ESOURCES

OOKS

Heitschmidt, R. K., ed. Grazing Management: An Ecological Perspective.

Portland, OR: Timber Press, 1991.

Spedding, C. R. W. Grassland Ecology. London: Oxford University

Press, 1971.

ERIODICALS

Senft, R., et al. “Large Herbivore Foraging and Ecological Hierarchies;

Landscape Ecology Can Enhance Traditional Foraging Theory.” Bioscience

37 (December 1987): 789–95.

Strickland, R. “Taking the Bull by the Horns: Conservationists Have Been

Wrangling Politely With Land Managers For Years—But Have Failed to

Halt Overgrazing Throughout the West.” Sierra 75 (September-October

1990): 46–48.

Overhunting

Overhunting is any

hunting

activity that has an adverse

impact on the total continuing population of a

species

With the tremendous increase in the human population

since the industrial revolution, there has been an ever increas-

ing use and, often, exploitation of many of the world’s

natu-

ral resources

. The demand for fish and shellfish has exem-

plified this misuse of natural resources. The amount of

hunting pressure that a species can tolerate depends on its

productivity, and it may change seasonally and annually be-

cause of

drought

habitat

alteration,

pollution

, or other

mortality

factors. Hunting which is well-regulated can be

sustained, and sportsmen in countries with regulated hunting

are quick to point out that they are not responsible for the

endangerment or

extinction

of any species.

In unregulated situations, however, overhunting does

occur, and it has endangered

wildlife

, even driving some

species to extinction. The great auk (Alca impennis), a large,

flightless, penguin-like bird of the North Atlantic coasts,

was so easy to catch that sailors could kill hundreds in a few

minutes, and by 1844 they had become extinct. Even the

world’s most abundant bird, the

passenger pigeon

(Ectopi-

stes migratorius), was driven to extinction by overhunting.

In the 1800s there were 3 to 5 billion passenger pigeons,

about one-fourth of all North American land birds, and

enormous flocks of them would darken the sky for days as

they flew overhead. One colony in Wisconsin covered 850

square miles (220,149 ha) and included 135 million adult

birds. Commercial hunting sent train loads of these birds

to markets, including 15 million birds from a single colony

in Michigan, and eliminated the species in the early 1900s.

There are several cases where overhunting has nearly

exterminated a species. In 1850 there were 60 million Ameri-

can

bison

(Bison bison) on the Great Plains of the United

States, and within 40 years, overhunting had reduced the

wild population to 150 individuals. At the turn of the cen-

Environmental Encyclopedia 3

Oxidation reduction reactions

tury, snowy egrets (Leucophoyx thula) were almost wiped

out by hunters who the sold the feathers to be made into

fashionable women’s hats. Many species of

whales

were

also driven to the brink of extinction by whalers.

Many species continue to be overhunted today. Al-

though protected by law, African

rhinoceroses

are endan-

gered by poachers who sell the horns to Yemen and China.

In Yemen the horns are used to make dagger handles for

wealthy businessmen, and in China they are made into an

aphrodisiac and fever-reducing drug which is reportedly use-

less. Likewise,

elephants

are being slaughtered for their

ivory tusks. There were 4.5 million elephants in 1970, and

by 1990, only 610,000.

Many large cat species are also threatened by overhunt-

ing, because the economic incentive to poach these animals

far outweighs the risks of being caught and fined. For exam-

ple, a Bengal tiger (Panthera tigris tigris) fur coat sells for

$100,000; an ocelot (Felis pardalis) skin sells for $40,000; a

snow leopard

(Panthera uncia) skin sells for $14,000; and

tiger meat sells for $629 per pound ($286/kg).

Even when appropriate hunting regulations do exist,

there are often not enough rangers or

conservation

officers

to enforce them. As species become more scarce, the demand

increases on the black market, inflating the price, and the

economic incentive for

poaching

only becomes greater. Un-

less appropriate laws are enacted and enforced other species

will become extinct from overhunting. See also Conservation;

Convention on International Trade in Endangered Species

of Fauna and Flora; Defenders of Wildlife; Endangered

species; Endangered Species Act; Fish and Wildlife Service;

IUCN—The World Conservation Union; Wildlife manage-

ment; Wildlife rehabilitation

[Ted T. Cable]

ESOURCES

OOKS

Ofcansky, T. P. Paradise Lost: A History of Game Preservation in East Africa.

Morgantown: West Virginia University Press, 1993.

Owens, D., and M. Owens. Eye of the Elephant: Life and Death in an

African Wilderness. New York: Houghton Mifflin, 1992.

ERIODICALS

Jackson, P. “They’ve Shot Miro.” International Wildlife 22 (November-

December 1992): 38–43.

Owl

see

Northern spotted owl

1044

Oxidation reduction reactions

An oxidation-reduction or redox reaction is transformation

involving electron transfer. It consists of a half reaction in

which a substance loses an electron or electrons (oxidation)

and another half reaction in which a substance gains an

electron or electrons (reduction).

The substance that gains electrons is the

oxidizing

agent

, while the substance that gives up electrons is the

reducing agent. Adding the two half equations algebraically

and eliminating the free electrons gives the complete oxida-

tion-reduction equation. This equation, however, is not an

assurance that the reaction will proceed spontaneously as

written. One way to know the direction of the reaction is

to determine the value of the standard free energy change,

⌬G

, and then to calculate the free energy change, ⌬G, for

the complete redox reaction. If the resulting value of ⌬Gis

negative, the reaction will proceed spontaneously as written.

If ⌬G is positive, the reaction can proceed spontaneously in

the opposite direction. If ⌬G is zero, the reaction is in

equilibrium.

Simple redox reactions occur with the direct transfer

of electrons from the reducing agent to the oxidizing agent.

An example is the reaction between

hydrogen

) and

chlorine

(Cl

) to form hydrogen chloride. In this reaction,

hydrogen, the reducing agent, donates two electrons to chlo-

rine which is the oxidizing agent. Because it gains electrons,

the oxidizing agent changes in valence and becomes more

negative or less positive. In the given example, the valence

of chlorine changes from 0 to -1. The reducing agent, on

the other hand, loses electrons and hence becomes more

positive. Thus hydrogen, being the reducing agent in the

given example, changes in valences from 0 to +1.

Some common applications of redox reactions in

wastewater

treatment are the

detoxification

of cyanide

and the precipitation of chromium. Highly toxic cyanide is

converted to nontoxic cyanate and finally to

carbon dioxide

and

nitrogen

gas by the action of strong oxidizing agents,

such as chlorine gas or sodium hypochlorite. In removing

hexavalent chromium, the objective is to reduce it to trivalent

chromium, which is less toxic and can be precipitated out

in the form of hydroxide. Hexavalent chromium is reduced

by sodium bisulfite or ferrous sulfate in an

acid

medium.

Lime can then be applied to precipitate out the trivalent

chromium as chromium hydroxide, which collects as a chem-

ical

sludge

upon settling.

In biochemical redox reactions, however, the electrons

go through a series of transfers before reaching the terminal

acceptor, which is oxygen in

aerobic systems

. Examples

of these electron carriers are NAD (nicotinamide adenine

dinucleotide), NADP (nicotinamide adenine dinucleotide

phosphate), and flavoproteins. In

anaerobic systems

, other

Environmental Encyclopedia 3

Ozonation

materials such as

nitrates

, sulfates, and

carbon

dioxide may

become the electron acceptor, as in the process of

denitrifi-

cation

in which nitrate (NO

) is reductively degraded to

molecular nitrogen (N

). In either case, organic or inorganic

matter, which serves as food for the

microorganisms

,is

the substance oxidized. A simplified stoichiometry of the

complete

aerobic

biochemical oxidation of glucose, for ex-

ample, produces six moles of carbon dioxide and six moles

of water with the release of 686 kilocalories per mole. See

also Corrosion and material degradation; Electron acceptor

and donor; Industrial waste treatment; Sewage treatment;

Waste management

[James W. Patterson]

ESOURCES

OOKS

Eckenfelder Jr., W. W. Industrial Water Pollution Control. New York:

McGraw-Hill, 1989.

Snoeyink, V. L., and D. Jenkins. Water Chemistry. New York: Wiley, 1980.

Oxidizing agent

Any substance that donates oxygen or that gains electrons

in a chemical reaction. Perhaps the most common example

of an oxidizing agent is the element oxygen itself. When a

substance burns, rusts, or decays, that substance combines

with oxygen in the air around it. Oxidizing agents can have

both beneficial and harmful environmental effects.

Chlorine

gas is used as an oxidizing agent to kill bacteria in the

purification of water.

Ozone

damages plant and animal cells

by oxidizing them.

Oxygen, dissolved

see

Dissolved oxygen

Ozonation

The process which takes advantage of the oxidizing proper-

ties of

ozone

is known as ozonation. Ozone can be used in

a variety of applications including the treatment of drinking

water, bottled water, beverages,

wastewater

, industrial

wastes, air pollutants, swimming pool water, and cooling

tower water. In addition, there are a number of proprietary

processes that use ozone, ranging from carpet cleaning to

the making of gourmet ice cubes. Ozonation consists of

four fundamental tasks: drying and cleaning the oxygen-

1045

containing feed-gas; generating ozone in a silent corona

discharge

generator; bringing the ozone into contact with

the material being treated; and finally destroying remaining

ozone prior to releasing the waste gas to the

atmosphere

All ozonation processes require ozone generation and con-

tacting, but not all applications require feed-gas preparation

and off-gas treatment.

Ozone can be generated by three processes: electrical

discharge,

photochemical reaction

with

ultraviolet radia-

tion

, and electrolytic reactions. The latter two methods pro-

duce very low concentrations of ozone, limiting their applica-

tion. Electrical discharge generators are currently the most

economical choice for producing large quantities of ozone.

Feed-gas must contain oxygen and be free of contaminants

such as particles,

hydrocarbons

, and water vapor. For opti-

mum production of ozone, the feed-gas should have a

dew

point

of at least -37°F (-40°C) and preferably -73°F (-60°C).

Small ozonation systems can use air which is dried before

entering the ozone generator. Larger systems may find pure

oxygen is economically viable. The temperature of the feed-

gas and the generator is one of the most important parame-

ters affecting the production of ozone. High temperatures

reduce the concentration of ozone and greatly decrease the

life of ozone in the gas phase. The

recycling

of ozone

process gases increases the concentration of

nitrogen

, which

leads to decreases in ozone production, and, in the presence

of water vapor, to the production of corrosive nitric

acid

Contacting ozone with the material to be treated is

complicated by several factors: ozone is reactive and disap-

pears, so it must be generated at the site where it is used,

and the waste ozone in the exhaust gas is toxic. When

choosing ozone contacting devices for an aquatic system,

two types of reactions must be taken into account. In mass-

transfer limited reactions ozone is being consumed faster

than it can be transferred to solution. In reaction rate limited

reactions ozone is in surplus in solution but the material

being oxidized is rate limiting, so that ozone is wasted.

Bubble-diffuser systems are commonly used in

water treat-

ment

because they are good compromises for satisfying the

need to control both mass-transfer and rate limited reactions.

However, in some aquatic applications in-line dissolution

and contacting may be the optimum technique for ozonating

the water in question.

Exhaust gas or off-gas requires treatment to remove

traces of ozone remaining in the gas after contacting. Ther-

mal destruction is one of the most commonly used methods

for removing ozone from the waste gas. Other methods

for destroying ozone include catalytic destruction, activated

carbon adsorption

, and zeolites. See also Industrial waste

treatment; Water treatment

[Gordon R. Finch]

Environmental Encyclopedia 3

Ozone

ESOURCES

OOKS

Langlais, B., D. A. Reckhow, and D. R. Brink, eds. Ozone in Water

Treatment: Application and Engineering. Chelsea, MI: Lewis Publishers,

1991.

Rice, R. G., and A. Netzer, eds. Handbook of Ozone Technology and Applica-

tions. Vol. 1. Ann Arbor, MI: Ann Arbor Science Publishers, 1982.

Rice, R. G., and A. Netzer, eds. Handbook of Ozone Technology and Applica-

tions. Vol. 2. Boston: Butterworth Publishers, 1984.

Ozone

Ozone is a toxic, colorless gas (but can be blue when in high

concentration) with a characteristic acrid odor. A variant of

normal oxygen, it had three oxygen atoms per molecule

rather than the usual two. Ozone strongly absorbs

ultravio-

let radiation

at wavelengths of 220 through 290 nm with

peak

absorption

at 260.4 nm. Ozone will also absorb infra-

red radiation at wavelengths in the range 9-10 ␮m. Ozone

occurs naturally in the ozonosphere (ozone layer), which

surrounds the earth, protecting living organisms at the earth’s

surface from ultraviolet radiation. The ozonosphere is lo-

cated in the

stratosphere

from 6–31 miles (10–50 km)

above the earth’s surface, with the highest concentration

between 7.5 and 12 miles (12 and 20 km). The concentration

of ozone in the ozonosphere is 1 molecule per 100,000

molecules, or if the gas were at standard temperature and

pressure, the ozone layer would be 0.12 inch (3 mm) thick.

However, the ozone layer absorbs about 90% of incident

ultraviolet radiation.

Ozone in the stratosphere results from a chemical

equilibrium between oxygen, ozone, and ultraviolet radia-

tion. Ultraviolet radiation is absorbed by oxygen and pro-

duces ozone. Simultaneously, ozone absorbs ultraviolet radi-

ation and decomposes to oxygen and other products.

Ozone

layer depletion

occurs as a result of complex reactions in

the

atmosphere

between organic compounds that react

with ozone faster than the ozone is replenished. Compounds

of most concern include the byproducts of ultraviolet degra-

dation of

chlorofluorocarbons

(CFCs),

chlorine

and flu-

orine.

Ozone is also a secondary air pollutant at the surface

of the earth as a result of complex chemical reactions between

sunshine and primary pollutants, such as

hydrocarbons

and

oxides of

nitrogen

. Ozone can also be generated in the

presence of oxygen from equipment that gives off intense

light, electrical sparks, or creates intense static electricity,

such as photocopiers and laser printers. Human olfactory

senses are very sensitive to ozone, being able to detect ozone

odor at concentrations between 0.02 and 0.05

parts per

million

. Toxic symptoms for humans from exposure to ozone

include headaches and drying of the throat and respiratory

1046

tracts. Ozone is highly toxic to many plant

species

and

destroys or degrades many building materials, such as paint,

rubber

, and some

plastics

. The total losses in the United

States each year due to ozone damage to crops, livestock,

buildings, natural systems, and human health is estimated

to be in the tens of billions of dollars. The threshold limit

value (TLV) for

air quality

standards is 0.1 ppm or 0.2 mg

per m

of air.

Industrial uses of ozone include chemical manufactur-

ing and air, water, and waste treatment. Industrial quantities

of ozone are typically generated from air or pure oxygen by

means of silent corona

discharge

. Ozone is used in

water

treatment

as a disinfectant to kill pathogenic

microorgan-

isms

or for oxidation of organic and inorganic compounds.

Combinations of ozone and

hydrogen

peroxide or ultravio-

let radiation in water can generate powerful oxidants useful

in breaking down complex synthetic organic compounds.

wastewater

treatment, ozone can be used to disinfect

effluents, or decrease their color and odor. In some industrial

applications, ozone can be used to enhance biodegradation

of complex organic molecules. Industrial cooling tower treat-

ment with ozone prevents transmission of airborne patho-

genic organisms and can reduce odor. See also Biodegradable;

Ozonation

[Gordon R. Finch]

ESOURCES

OOKS

Horva

th, M., L. Bilitzky, and J. Hu

ttner. Ozone. Amsterdam: Elsevier,

1985.

Kaufman, D. G., and C. M. Franz. Biosphere 2000: Protecting Our Global

Environment. New York: HarperCollins College Publishers, 1993.

Ozone layer depletion

Destroying the ozone shield

Ozone

, a form of oxygen consisting of three atoms

of oxygen instead of two, is considered an air pollutant when

found at ground levels and is a major component of

smog

It is formed by the reaction of various air pollutants in the

presence of sunlight. Ozone is also used commercially as a

bleaching agent and to purify municipal water supplies. Since

ozone is toxic, the gas is harmful to health when generated

near the earth’s surface. Because of its high rate of break-

down, such ozone never reaches the upper

atmosphere

But the ozone that shields the earth from the sun’s

radiation is found in the

stratosphere

, a layer of the upper

atmosphere found 9–30 mi (15–50 km) above ground. This

ozone layer is maintained as follows: the action of ultraviolet

light breaks O

molecules into atoms of elemental oxygen

(O). The elemental oxygen then attaches to other O

mole-