Environmental Encyclopedia

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Dam removal

There are over 77,000

dams

of significant size (over 6 ft

[1.8 m] tall) in the United States, and tens of thousands of

additional uncharted smaller dam structures. Constructed for

the purposes of harnessing

water resources

for

irrigation

water supply, and hydroelectric power, dams can be a useful

ally for human needs; they also have a major and long-term

impact on the entire river

ecosystem

Since 1912, over 460 dams have been removed from

United States waterways for both safety and environmental

reasons. Dams associated with hydroelectric power projects

are decommissioned after their useful life and removal is

often recommended to return river ecosystems back to their

natural state.

Damaged or obsolete dam structures may present a

safety hazard, particularly if they are no longer regularly

maintained. Upkeep of a dam is expensive, and local taxpay-

ers may bear the brunt of caring for a dam that no longer

serves any practical function. Finally, abandoned or unused

dams can be aesthetically unpleasant in an otherwise scenic

natural area.

Dams and their associated reservoirs can significantly

impact river ecosystems and alter their natural course. The

structures raise water temperatures, obstruct debris and

nu-

trient

flow, and prevent

sediment

dispersal. And they have

an enormous impact on runs of

salmon

, steelhead, and other

migratory fish, often in a relatively short period of time.

For example, according to the National

Fish and Wildlife

Service

the first dam to be built across the Connecticut

River in 1798 resulted in the

extinction

of native Atlantic

salmon stock in the river just a few years later. Despite the

integration of fish lifts and fish ladders into modern dams,

populations of native fish stocks are still greatly depleted by

dam structures. Currently, several dams in the northwest are

being removed to replenish many of these

species

which

are protected under the

Endangered Species Act

There can be some short-term negative environmental

issues associated with dam removal projects. Contaminated

347

sediment that may collect under a dam can disperse through-

out the area, and populations of non-native species that have

settled in the dam-altered

habitat

may decline once the

dam has been removed. However, in most cases dam removal

encourages re-establishment of the native ecosystem and

organisms.

Depending on its location and the ownership of the

dam, removal may be governed by a variety of federal, state,

and local authorities. For federal dam projects, the U.S.

Army Corps of Engineers

and/or the

Bureau of Reclama-

tion

are charged with planning and completion of removal

projects. However, only 3% of dams included in the U.S.

Army Corps of Engineers national inventory of dams are

owned by the federal government, compared with 58% of

privately-owned dams.

Even if ownership of a dam is private, the waterways

the structure harnesses are public and there is still a signifi-

cant amount of regulatory oversight on all levels of govern-

ment. The U.S.

Environmental Protection Agency

(EPA)

and some state authorities typically request a full environ-

mental assessment and written report called an “Environ-

mental Impact Statement” (or EIS). The EIS outlines differ-

ent scenarios for completion of a dam removal project, from

no action (letting the dam naturally deteriorate over time)

to full dismantling and removal with additional clean-up of

dam sediments. It then describes the impact each approach

will have on the ecosystem surrounding the dam site.

[Paula Anne Ford-Martin]

ESOURCES

OOKS

McNully, Patrick. Silenced Rivers: The Ecology and Politics of Large Dams.

2nd edition. London: Zed Books, 2001.

ERIODICALS

Baish, Sarah K., et al. “The Complex Decision-Making Process for Remov-

ing Dams.” Environment 44, no. 4 (May 2002): 20.

Environmental Encyclopedia 3

Dams (environmental effects)

THER

American Rivers, Friends of the Earth, & Trout Unlimited. Dam Removal

Success Stories: Restoring Rivers through Selective Removal of Dams that Don’t

Make Sense. December 1999.

U.S. Army Corps of Engineers and the Federal Emergency Management

Agency. National Inventory of Dams. [June 2002]. <http://crunch.tec.ar-

my.mil/nid/webpages/nid.cfm>.

RGANIZATIONS

American Rivers, 1025 Vermont Ave., N.W. Suite 720 , Washington,

DC USA 20005 (202)347-7550, Fax: (202)347-9240, Email:

amrivers@amrivers.org, <http://www.amrivers.org/damremoval/

default.htm>

Dams (environmental effects)

Most dams are built to control flood hazards, to store water

for

irrigation

or other uses, or to produce electricity. Along

with these benefits come environmental costs including ri-

parian

habitat

loss, water loss through evaporation and

seepage

erosion

, and declining

water quality

. Farther-

reaching consequences of dams include changes in

ground-

water

flow and the displacement of human populations.

Riparian, or stream–side, habitats suffer both above

and below dams. Valuable ecological zones that support

specialized plants, riparian environments, and nearby shal-

lows provide food and breeding grounds for birds, fish, and

many other animals. Upstream of a dam, impounded water

drowns riparian communities. Because reservoirs can fill

hundreds of miles of river channel, and because many rivers

have a long sequence of dams and reservoirs, habitat drown-

ing can destroy a great deal of river

biodiversity

. Down-

stream, shoreline environments dry up because of water di-

versions (for irrigation or urban use) or because of

evaporation and seepage losses in the

reservoir

. In addition,

dams interrupt the annual floods that occur naturally on

nearly all rivers. Seasonal

flooding

fertilizes and waters flood

plains and clears or redistributes debris in river channels.

These beneficial effects of flooding cease once a river is

dammed.

Dams and reservoirs alter

sediment

deposition in riv-

ers. Most rivers carry large amounts of suspended

silt

and

sand, and dams trap sediments normally deposited down-

stream. Below the dam, erosion reshapes river channels once

sediment deposition ceases. If erosion becomes extreme,

bridges, levees, and even river deltas can be threatened.

Meanwhile, sediment piling up in the still waters of the

reservoir behind the dam decrease water storage capacity.

An increasingly shallow reservoir also becomes gradually

warmer. Oxygen content decreases as the water temperature

rises; fish populations fall, and proliferating algae and aquatic

plants can begin to block the dam’s water intakes. In

arid

regions a higher percentage of river water evaporates as the

reservoir becomes shallower. Evaporating water leaves be-

348

hind salts, which further decrease water quality in the reser-

voir and river.

Water losses from evaporation can be extreme: Lakes

Powell and Mead on the

Colorado River

lose about 3 billion

cu ft (1 billion cu m) of water to evaporation each year;

Egypt’s Lake Nasser, on the Nile River, loses about 45 billion

cu ft (15 billion cu m). Water losses also result from seepage

into bedrock. As river water enters groundwater, water tables

usually rise around a reservoir. In arid regions increased

groundwater can increase local fertility (sometimes endan-

gering delicate dry-land plant

species

), but in moister re-

gions excessive groundwater can cause swamping. Evapora-

tion from exposed groundwater can leave higher salt

concentrations in the

soil

. The most catastrophic results of

reservoir seepage into groundwater occur when saturated

rock loses its strength. In such events valley walls can col-

lapse, causing dam failure and disastrous flooding down-

stream.

Perhaps the most significant environmental effect of

dams results from the displacement of human populations.

Because people normally settle along rivers, where water

for drinking, irrigation, power, and transport are readily

available, reservoir flooding can displace huge populations.

The planned

Three Gorges Dam

on China’s Chang Jiang

(Yangtze River) will displace 1.4 million people and flood

some of western China’s best agricultural land. A series of

dams on India’s Narmada river will inundate the homes of

1.5 million people along with 600,000 acres (150,000 ha)

of farm land. In both cases, people will need to find new

places to live and clear new land to grow food. Such ripple

effects carry a dam’s influence far beyond its immediate

proximity.

Where dams are needed for power, they can have a

positive effect in offsetting environmental costs associated

with other power sources. Hydropower is cleaner and safer

than

nuclear power

. Water turbines are also cleaner than

coal-fired generators. Furthermore, both nuclear and

coal

power require extensive mining, with environmental costs

far more severe than those of even a large dam.

[Mary Ann Cunningham Ph.D.]

ESOURCES

OOKS

Goldsmith, E., and N. Hidyard, eds. The Social and Environmental Effects

of Large Dams. (3 Vols.) New York: Wiley, 1986.

ERIODICALS

Esteva, G., and M. S. Prakash. “Grassroots Resistance to Sustainable Devel-

opment.” The Ecologist 22 (1992): 45-51.

THER

Driver, E. E., and W. O. Wunderlich, eds. Environmental Effects of Hydrau-

lic Engineering Works. Proceedings of an International Symposium Held

Environmental Encyclopedia 3

Charles Robert Darwin

at Knoxville, Tennessee, Sept. 12-14, 1978. Knoxville: Tennessee Valley

Authority, 1979.

Danube River

see

Eastern European pollution

Jay Norwood “Ding” Darling (1876 –

1962)

American environmental cartoonist

Most editorial page cartoonists focus on the tough job of

meeting daily deadlines, satisfied that their message will

influence public opinion through their drawings. Jay Nor-

wood “Ding” Darling, however, drew Pulitzer prize-winning

cartoons, but was also immersed in

conservation

action,

emerging as one of the great innovators in the conservation

movement of the first half of the twentieth century.

Norwood, Michigan, was Darling’s namesake birth-

place, but he grew up in Elkhart, Indiana, and attended high

school in Sioux City, Iowa, at a time when the area was

relatively undeveloped. Wandering the prairies of nineteenth

century Iowa, Nebraska, and South Dakota instilled in him

a life-long love of the outdoors and

wildlife

After an uneven beginning, Darling graduated from

Beloit College in Wisconsin with a degree in biology. (At

one college, during one semester, biology was the only course

he passed). And he was expelled from Beloit for a year for

caricaturing individuals in the college faculty and administra-

tion. Building on an early interest in sketching (and the

cartooning skills developed in college) Darling went on to

a half-century of drawing political cartoons, including some

of the most memorable conservation/environmental cartoons

of the twentieth century. His first job (1900) was as a reporter

(and sometimes caricaturist) in Sioux City, but six years

later, he was hired by the Des Moines Register and Leader,

where his primary task was to produce a cartoon each day

for the editorial page. He retired from that same paper in

1949. Darling did spend two years as an editorial cartoonist

for the New York Globe, but returned to Iowa at the first

real opportunity.

The only other significant period away from his Des

Moines newspaper position illustrates his action mode as a

conservationist. Darling was active in political life generally,

and this involvement often reflected his love of the outdoors

and his dismay at what he felt the United States was doing

to destroy its natural resource base. He helped organize the

Izaak Walton League

in Des Moines, was active in the

landscaping of local parks, and worked to establish the first

cooperative wildlife research unit at Iowa State College in

349

Ames, a unit that served as a model for the establishment

of similar units in other states.

Perhaps his greatest impact as an activist resulted from

his appointment, by President Franklin Roosevelt, as head

of the U.S. Bureau of Biological Survey, predecessor of the

U.S.

Fish and Wildlife Service

. He was only in the position

for two years, not being happy as a bureaucrat and not happy

away from Iowa. But he was reportedly very effective in the

job, “raiding” (in Roosevelt’s words) the U.S. Treasury for

scarce depression-era funds for waterfowl

habitat

restora-

tion, and initiating the duck stamp program which over the

years has funded the acquisition of several million acres

added to the

National Wildlife Refuge

system. He also

used his drawing skills to design the first duck stamp, as

well as the flying goose that has become the signpost and

symbol of the national

wildlife refuge

system.

Darling was also one of the founders, and then first

President of the

National Wildlife Federation

in 1938. He

later criticized the organization, and the proliferation of

conservation organizations in general, because he first envi-

sioned the Federation as an umbrella for conservation efforts

and thought the emergence of too many groups diluted the

focus on solving conservation and environmental problems.

Until the end of his life, he tried, and failed, to organize a

conservation clearing house that would refocus the conserva-

tion effort under one heading.

He put into all his efforts lessons of interdependence

learned early from biology classes at Beloit College: “Land,

water, and vegetation are [interdependent] with one another.

Without these primary elements in natural balance, we can

have neither fish nor game, wild flowers nor trees, labor nor

capital, nor sustaining habitat for humans.”

[Gerald L. Young Ph.D.]

ESOURCES

OOKS

Lendt, David L. Ding: The Life of Jay Norwood Darling. Ames, IA: Iowa

State University Press, 1979.

ERIODICALS

Dudley, Joseph P. “Jay Norwood ’Ding’ Darling: A Retrospective.” Conser-

vation Biology 7, no. 1 (March 1993): 200–203.

“Jay N. Darling: More Than a Cartoonist.” The World of Comic Art 1, no.

1 (June 1966): 18–25.

Charles Robert Darwin (1809 – 1882)

English naturalist

Darwin, an English biologist known for his theory of

evolu-

tion

, was born at Shrewsbury, England, on February 12,

1809. He was born on the same day and the same year as

Environmental Encyclopedia 3

Dead zones

Abraham Lincoln, a coincidence that may alert American

readers to Darwin’s era. He studied, traveled, and published

his famous On the Origin of Species (1859) just prior to the

American Civil War.

Darwin’s father was an affluent physician and his

mother the daughter of the potter Josiah Wedgwood.

Charles married Emma Wedgwood, his first cousin, in 1839.

Due to his family’s wealth, Darwin was made singularly free

to pursue his interest in science.

Darwin entered Edinburgh to study medicine, but, as

he described in his autobiography, lectures were “intolerably

dull,” human anatomy “disgusted” him, and he experienced

“nausea” in seeing surgery. He subsequently entered Christ’s

College, Cambridge, to prepare for Holy Orders in the

Church of England. While at Cambridge, Darwin became

intensely interested in geology and botany, and because of

his knowledge in these sciences he was asked to join the

voyage of the HMS Beagle. Darwin’s experiences during

the circumnavigational trek of the Beagle were of seminal

importance in his later views on evolution.

Darwin’s On the Origin of Species is a monumental

catalog of evidence that evolution occurs, together with the

description of a mechanism that explains such evolution.

This “abstract” of his notions on evolution was hurried to

publication because of a letter Darwin received from Alfred

Russell Wallace expressing similar views. Darwin’s evidence

for evolution was drawn from comparative anatomy, embry-

ology, distribution of

species

, and the fossil record. He

believed that species were not immutable but evolved into

other species. But how? His theory of evolution by natural

selection is based on the premise that species have a great

reproductive capacity. The production of individuals in ex-

cess of the number that can survive creates a struggle for

survival. Variation between individuals within a species was

well documented. The struggle for survival, coupled with

variation, led Darwin to postulate that those individuals

with favorable variations would have an enhanced survival

potential and hence would leave more progeny and this

process would lead to new species. This notion is sometimes

referred to as “survival of the fittest.” While the theory of

evolution by natural selection was revolutionary for its day,

essentially all biologists in the late twentieth century accept

Darwinian evolution as fact.

The first edition of the Origin had a printing of 1,250

copies. It sold out the first day. Darwin was an extraordinarily

productive author for someone who considered himself to

be a slow writer. Among his other books are Structure and

Distribution of Coral Reef (1842), Geological Observations on

Volcanic Islands (1844), On the Various Contrivances by which

British and Foreign Orchids are Fertilized by Insects (1862),

Insectivorous Plants (1875), and On the Formation of Vegetable

Mould through the Action of Worms (1881). The last book,

350

Charles Darwin. (Photo Researchers Inc. Reproduced

by permission.)

of interest to ecologists and gardeners, was published only

six months prior to Darwin’s death.

Darwin died at age 73 and is buried next to Sir Isaac

Newton at Westminster Abbey in London.

[Robert G. McKinnell]

ESOURCES

OOKS

Barlow, N. The Autobiography of Charles Darwin, 1809–1882. With original

omissions restored. Edited with appendix and notes by his granddaughter.

New York: Norton, 1958.

Darwin, C. The Voyage of the Beagle. New York: Bantam Books, 1958.

Peckham, M., ed. The Origin of Species by Charles Darwin. A Variorum

Text. Philadelphia: University of Pennsylvania Press, 1959.

DDT

see

Dichlorodiphenyl-trichloroethane

Dead zones

The term dead zone refers to those areas in aquatic environ-

ments where there is a reduction in the amount of

dissolved

oxygen

in the water. The condition is more appropriately

Environmental Encyclopedia 3

Dead zones

called hypoxia or hypoxic waters or zones. Hypoxia in marine

environments is determined when the dissolved oxygen con-

tent is less than 2–3 milligrams/liter. Five to eight milli-

grams/liter of dissolved oxygen is generally accepted as the

normal level for most marine life to survive and reproduce.

Dead zones can not only reduce the numbers of marine

animals, but they can also change the

nature

of the

ecosys-

tem

within the hypoxic zone.

The main cause of oxygen depletion in aquatic envi-

ronments is eutrophication. This process is a chain of events

that begins with

runoff

rich in

nitrogen

and

phosphorus

that makes its way into rivers that eventually

discharge

into estuaries and river deltas. This nutrient-laden water,

combined with sunlight, stimulates plant growth, specifically

algae, seaweed, and

phytoplankton

. When these plants die

and fall to the ocean floor, they are consumed by bacteria

that use large amounts of oxygen, thereby depleting the

environment

of oxygen.

Dead zones can lead to significant shifts in

species

balances throughout an ecosystem. Species of aquatic life

that can leave these zones—such as fish and shrimp—do so.

Bottom-growing plants, shellfish, and others that cannot

leave, die, creating an area devoid of aquatic life. This is the

reason the term dead zone has been aptly used (especially by

the media) to describe these areas.

Eutrophication of estuaries and enclosed coastal seas

has often been a natural phenomenon when offshore winds

and water currents force deep nutrient-laden waters to rise

to the surface, stimulating algae bloom. The timing and

duration of these conditions varies from year to year and

within seasons. Climatic conditions and catastrophic

weather events can influence the rapidity hypoxia can occur.

In the past, these natural hypoxic areas were limited, and

the marine environment could recover quickly.

Nutrient

availability, temperature, energy supply (i.e.,

soluble

carbon

for most

microorganisms

or light and

car-

bon dioxide

for plants), and oxygen status all affect the

growth and sustainability of aquatic plants and animals. One

condition that perpetuates hypoxia is elevated temperatures

because the ability of water to hold oxygen (i.e. water solubil-

ity) decreases with increasing temperature. Situations that

promote consumption of oxygen such as plant and animal

respiration

and

decomposition

can also lead to hypoxic

conditions in water. Therefore, situations that stimulate

plant (i.e. phytoplankton, benthic algae and macroalgae)

growth in water can lead indirectly to hypoxic conditions.

Algal growth can be accelerated with elevated levels of carbon

dioxide and certain nutrients (especially nitrogen and phos-

phorus), provided adequate sunlight is available. Low

sedi-

ment

loads also support increased algal growth because the

water is less turbid allowing more light to penetrate to the

bottom.

351

In the last two decades of the twentieth century, the

increased incidence of hypoxia and the expanded size of

dead zones have been the result of increased nutrients coming

from human sources. Runoff from residential and agricul-

tural activities are loaded with fertilizers, animal wastes, and

sewage that have specific nutrients that can stimulate plant

growth. In the United States, nutrient runoff has become

a major concern for the entire interior watersheds of the

Mississippi River Basin which drains into the Gulf of

Mexico.

Hypoxic waters occur near the mouths of many large

rivers around the world and in coastal estuaries and enclosed

coastal seas. In fact, over 40 hypoxic zones have been identi-

fied throughout the world. Robert J. Diaz from the Virginia

Institute of Marine Science has studied the global patterns

of hypoxia and has concluded that the extent of these zones

has increased over the past several decades. Hypoxic zones

are occurring in the Baltic Sea, Kattegat, Skagerrak Dutch

Wadden Sea,

Chesapeake Bay

, Long Island Sound, and

northern Adriatic Sea, as well as the extensive one that

occurs at the mouth of the Mississippi River in the Gulf of

Mexico.

It is interesting to note that one of the largest hypoxic

zones documented occurred in conjunction with the increase

in ocean temperatures associated with

El Nin

. This weather

event occurs periodically off the west coast of North and

South America, and influences not only the winter weather

in North America, but also affects the anchovy catch off

Peru in the Pacific. This in turn, affects the worldwide price

for protein meal and has a direct impact on soybean farmers

(since this is another major source of protein for this

product).

The large hypoxic zone in the northern Gulf of Mexico

occurs where the Mississippi and Atchafalya rivers enter the

ocean. The zone was first mapped in 1985, and has doubled

in size since then. The Gulf of Mexico dead zone fluctuates

in size depending on the amount of river flow entering the

Gulf, and on the patterns of coastal winds that mix the

oxygen-poor bottom waters of the Gulf with Mississippi

River water. The zone in 1999 exceeded 8,006 mi

(20,720

) in area, making it one of the largest in the world. This

zone fluctuates seasonally, as do others. It can form as early

as February and last until October. The most widespread

and persistent conditions exist from mid-May to mid-Sep-

tember.

Recent research has shown that increased nitrogen

concentrations in the river water, which act like

fertilizer

stimulate massive phytoplankton blooms in the Gulf. Bacte-

ria decomposing the dead phytoplankton consume nearly all

of the available oxygen. This, combined with a seasonal

layering of the fresh water from the river and salt water in

Environmental Encyclopedia 3

Debt for nature swap

the Gulf, results in the zone of low-dissolved oxygen. Within

the zone there are very small fish and shellfish populations.

The effect of periodic events on the transport of nutri-

ents to the Gulf, derived primarily from fertilizer in areas

of intensive agriculture in the upper Mississippi River Basin,

have been implicated as the most likely cause. The largest

amount of nutrients is delivered each year after the spring

thaw when streams fill and concentrations of nutrients, such

as nitrogen, are highest. In addition, during extreme high-

flow events, such as those that occurred during the floods

of 1993, very high amounts of nutrients are transported to

the Gulf. Levels were 100% higher in that year than in

other years.

The nature of the hypoxia problem in the Gulf is

complicated by the fact that some nutrient load from the

Mississippi River is vital to maintain the productivity of the

Gulf fisheries but in levels considerably lower than are now

entering the marine system. Approximately 40% of the U.S.

fisheries landings comes from this area, including a large

amount of the shrimp harvest. In addition, the area also

supports a valuable sport fishing industry. The concern is

that the hypoxic zone has been increasing in size since the

1960s due to human activities in the Mississippi

Watershed

that have increased nitrogen loads to the Mississippi River.

The impact of an expanding Gulf hypoxia include: large

algal blooms that affect other aquatic organisms, altered

ecosystems with changes in plant and fish populations (i.e.,

lower

biodiversity

), reduced economic productivity in both

commercial and recreational fisheries, and both direct and

indirect impact on fisheries such as direct

mortality

and

altered

migration

patterns which may lead to declines in

populations.

Studies were conducted during the 1990s on the

sources of increased nutrient concentrations within the Mis-

sissippi River. A significant amount of nutrients delivered

to the Gulf come from the Upper Mississippi and Ohio

River watersheds. The amount of dissolved nitrogen and

phosphorus in the waters of the Mississippi has more than

doubled since 1960. The principal areas contributing nutri-

ents are streams draining the corn belt states, particularly

Iowa, Illinois, Indiana, Ohio, and southern Minnesota.

About 60% of the nitrate transported by the Mississippi

River comes from a land area that occupies less than 20%

of the basin. These watersheds are predominantly agricul-

tural and contain some of the most productive farmland in

the world. This area produces approximately 60% of the

nation’s corn. The U.S.

Geological Survey

has estimated

that 56% of the nitrogen entering the Gulf hypoxic zone

originates from fertilizer. Potential agricultural sources

within these regions include runoff from cropland, animal

grazing areas,

animal waste

facilities, and input from ag-

ricultural

drainage

systems. The contributions to nutrient

352

input from sources such as

atmospheric deposition

, coastal

upwelling, and industrial sources within the lower Missis-

sippi Watershed are being evaluated also. It is unclear what

effect the damming and channelization of the river for navi-

gation has on nutrient delivery. The dead zone area in the

Gulf will continue to be monitored to determine whether

it continues to expand.

In the meantime, efforts to reduce nutrient

are being undertaken in agricultural areas across the water-

shed. Several strategies to reduce nutrient loading have been

drafted. They are: a reduction in nitrogen-based fertilizers

and runoff from

feedlots

, planting alternative crops that do

not require large amounts of fertilizers, removing nitrogen

and phosphorus from

wastewater

, and restoring

wetlands

so that they can act as reservoirs and

filters

for nutrients.

Depending on whether the zone continues to expand or

decreases as nutrient levels diminish will determine whether

it remains a significant environmental problem in the Gulf

of Mexico. Knowledge gained from the study of changing

nutrient loads in the Mississippi River will be useful in

addressing similar problems in other parts of the world.

[James L. Anderson and Marie H. Bundy]

ESOURCES

ERIODICALS

Rabalais, N. N., R. E. Turner, D. Justic, Q. Dortch, W. J. Wisenman,

Jr., and B. K. Sen Gupta. “Nutrient changes in the Mississippi River and

septum responses on the adjacent continental shelf.”Estuaries 19, no. 2B

(1996): 386-407.

Turner, R.E., and N.N. Rabalais. “Changes in Mississippi River water

quality this century: Implications for coastal food webs.”Bio Science 41

(1991): 140-147.

Debt for nature swap

Debt for

nature

swaps are designed to relieve developing

countries of two devastating problems: spiraling debt bur-

dens and

environmental degradation

. In a debt for nature

swap, developing country debt held by a private bank is sold

at a substantial discount on the secondary debt market to an

environmental

nongovernmental organization

(NGO).

The NGO cancels the debt if the debtor country agrees to

implement a particular environmental protection or

conser-

vation

project. The arrangement benefits all parties involved

in the transaction. The debtor country decreases a debt bur-

den that may cripple its ability to make internal investments

and generate economic growth. Debt for nature swaps may

also be seen as a good alternative to defaulting on loans,

which hurts the country’s chances of receiving necessary

loans in the future. In addition, the country enjoys the bene-

fits of curbing environmental degradation. The creditor

(bank) decreases its holdings of potentially bad debt, which

Environmental Encyclopedia 3

Debt for nature swap

may have to be written off at a loss. The NGO experiences

global environmental improvement.

Debt for nature swaps were first suggested by Thomas

Lovejoy in 1984. Swaps have taken place between Bolivia,

Costa Rica, and Ecuador and NGOs in the United States.

The first debt for nature swap was implemented in Bolivia

in 1987.

Conservation International

, an American NGO,

purchased $650,000 of Bolivia’s foreign debt from a private

bank in the United States at a discounted price of $100,000.

The NGO then swapped the face value of the debt with the

Bolivian government for “conservation payments-in-kind,”

which involved a conservation program in a 3.7 million acre

(1.5 million ha) tropical forest region implemented by the

government and a local NGO.

Despite the benefits associated with debt for nature

swaps, implementation has been minimal so far. Less than

two percent of the $38 billion in debt for equity swaps have

been debt for nature swaps. A lack of incentives on the part

of the debtor or the creditor and the lack of well-developed

supporting institutional infrastructure can hinder progress

in arranging debt for nature swaps.

If a debtor country is unable to repay foreign debt, it

has the option of defaulting on the loans or agreeing to a

debt for nature swap. The country has an incentive to agree

to a debt for nature swap if defaulting is not a viable option

and if the benefits of decreasing debt through a swap out-

weigh the costs of implementing a particular environmental

protection project. The cost of the environmental protection

programs can be substantial if the developing country does

not have the appropriate institutional infrastructure in place.

The program will require the input of professional public

administrators and environmental experts. Without institu-

tions to support these individuals, the developing countries

may find it impossible to carry out the programs they promise

to undertake in exchange for cancellation of the debt. If, in

addition, the debtor country is highly capital-constrained,

then it might not give high priority to the benefits of an

environmental investment.

Whether the creditor has an incentive to sell a debt

on the secondary debt market to an NGO depends on the

creditor’s estimate of the likelihood of receiving payment

from the developing country; on the proportion of potentially

bad credit the creditor is holding; and on its own financial

situation. If the NGOs are willing to pay the price demanded

by private banks for developing country debt and swap it

for environmental protection projects in the debtor countries,

they will have the incentive to pursue debt for nature swaps.

Benefits that may be taken into account by the NGOs

are those commonly associated with environmental protec-

tion. Many developing countries hold the world’s richest

tropical rain forests, and the global community will benefit

greatly from the preservation of these forests. Tropical forests

353

hold a great deal of

carbon dioxide

, which is released into

the

atmosphere

and contributes to the

greenhouse effect

when the forests are destroyed. Another benefit is known

as “option value,” the value of retaining the option of future

use of plant or animal resources that might otherwise become

extinct. Although we may not know at present of what use,

if any, these

species

might be, there is a value associated

with preserving them for unknown future use. Examples

of future uses might be pharmaceutical remedies, scientific

understanding or

ecotourism

. In addition, NGOs may at-

tach “existence value” to environmental amenities. Existence

value refers to the value placed on just knowing that natural

environments exist and are being preserved. Many NGOs

believe preservation is important so that

future generations

can enjoy the

environment

. This value is known as “bequest

value.” Finally, the NGO may be interested in decreasing

hunger and poverty in developing countries, and both the

reduction of external debt and the slowing of the depletion

natural resources

in developing countries is perceived

as a benefit for this purpose.

To make a swap attractive, however, the NGO must

be assured that the environmental project will be carried

out after the debt has been canceled. Without adequate

enforcement and assistance, a country might promise to

implement an environmental project without being able or

willing to follow through. Again, the solution to this problem

lies in the development of institutions that are committed

to monitoring and giving assistance in the implementation

of the programs. Such institutions might encourage long-

term relationships between the debtor and NGO to facilitate

a structure by which debt is canceled piecemeal on the condi-

tion that the debtor continues to comply with the agreement.

A complicating factor that may affect an NGO’s

cost-

benefit analysis

of debt for nature swaps in the future is

that, as the number of swaps and environmental protection

projects increases, the value to be derived from any additional

projects will decrease, due to diminishing marginal returns.

As described above, the benefits associated with debt

for nature swaps both for the debtor countries and NGOs

hinge on the presence of supporting institutions in the devel-

oping countries. It is particularly important to promote the

establishment of appropriate, professionally managed public

agencies with adequate resources to hire and maintain envi-

ronmental experts and managers. These institutions should

be responsible for planning and implementing the programs.

It should be noted that, although large debt burdens

and environmental degradation are both serious problems

faced by many developing countries, there is no direct linkage

between them. Nevertheless, debt for nature swaps are an

intriguing remedy that seems to address both problems si-

multaneously. As the quantity and magnitude of swaps so

far have been relatively small, it is impossible to say how

Environmental Encyclopedia 3

Deciduous forest

successful a remedy it may be on a larger scale. It is clear,

though, that the future of debt for nature swaps depends on

the development of appropriate incentives to all parties in

the swap and on the development of institutions to support

the fulfillment of the agreements.

[Barbara J. Kanninen]

ESOURCES

ERIODICALS

Hansen, S. “Debt for Nature Swaps: Overview and Discussion of Key

Issues.” Ecological Economics 1 (1989): 77-93.

Lovejoy, T. E. “Aid Debtor Nations’ Ecology.” New York Times (4 October

1984): A31.

Deciduous forest

Deciduous forests are made of trees that lose their leaves

seasonally and are leafless for part of each year. The tropical

deciduous forest is green during the rainy season and bare

during the annual

drought

. The temperate deciduous forest

is green during the wet, warm summers and leafless during

the cold winters with the leaves turning yellow and red before

falling. Temperate deciduous forests once covered large por-

tions of Europe, eastern United States, Japan, and eastern

China.

Species

diversity is highest in Asia and lowest in

Europe. In the United States deciduous forest, 67 species

of trees exist.

Decline spiral

A decline spiral is the destruction of a

species

ecosystem

biosphere

in a continuing downward trend, leading to

ecosystem disruption and impoverishment. The term is

sometimes used to describe the loss of

biodiversity

, when

a catastrophic event has led to a sharp decline in the number

of organisms in a

biological community

In areas where the

habitat

is highly fragmented either

due to human intervention or natural disaster, the loss of

species is markedly accelerated. Loss of species diversity

often initiates a downward spiral, as the weakening of even

one plant or animal in an ecosystem, especially a

keystone

species

, can lead to the malfunctioning of the biological

community as a whole.

Biodiversity exists at several levels within the same

community; it can include ecosystem diversity, species diver-

sity, and genetic diversity. Ecosystem diversity refers to the

different types of landscapes that are home to living organ-

isms. Species diversity refers to the different types of species

in an ecosystem. Genetic diversity refers to the range of

characteristics in the DNA of the plants and animals of a

354

species. A catastrophic event that affects any aspect of the

diversity in an ecosystem can start a decline spiral.

Any major catastrophe that results in a decline in

biospheric quality and diversity, known as an ecocatastrophe,

may initiate a decline spiral.

Herbicide

and

pesticide

used

in agriculture, as well as other forms of

pollution

; increased

use of

nuclear power

, and exponential

population growth

are all possible contributing factors. The Lapp reindeer herds

were decimated by fallout from the nuclear accident at Cher-

nobyl in 1986. Similarly, the oil spill from the

Exxon Valdez

in 1989 led to a decline spiral to the Gulf of Alaska

ecosystem.

The force that begins a decline spiral can also be indi-

rect, as when

acid rain

air pollution

water pollution

,or

climate

change kill off many plants or animals in an ecosys-

tem. Diversity can also be threatened by the introduction

of non-native or

exotic species

, especially when these spe-

cies have no natural predators and are more aggressive than

the native species. In these circumstances, native species can

enter into a decline spiral that will impact other native species

in the ecosystem.

Restoration ecology

is a relatively new discipline that

attempts to recreate or revive lost or severely damaged ecosys-

tems. It is a hands-on approach by scientists and amateurs

alike designed to reverse the damaging trends that can lead

toward decline spirals. Habitat rebuilding for

endangered

species

is an example of restoration

ecology

. For example,

the Illinois chapter of

The Nature Conservancy

has recon-

structed an oak-and-grassland

savanna

in Northbrook, Illi-

nois, and a

prairie

in the 100-acre (40-ha) ring formed by

the underground Fermi National Accelerator Laboratory at

Batavia, Illinois. Since it is easier to reintroduce

flora

than

the

fauna

into an ecosystem, practitioners of restoration

ecology concentrate on plants first. When the plant mix is

right, insects, birds, and small animals return on their own

to the ecosystem.

[Linda Rehkopf]

ESOURCES

OOKS

Ehrlich, P., and J. Roughgarden. The Science of Ecology. New York: Macmil-

lian, 1987.

May, R. M. Stability and Complexity in Model Ecosystems. Princeton, NJ:

Princeton University Press, 1973.

Decomposers

Decomposers (also called saprophages, meaning “corpse

eating") are the organisms which perform the critical task

decomposition

nature

. They include bacteria,

fungi

and

detritivores

that break down dead organic matter, re-

Environmental Encyclopedia 3

Deep ecology

leasing nutrients back into the

ecosystem

. Fungi are the

dominant decomposers of plant material, and bacteria pri-

marily break down animal matter. Decomposers secrete en-

zymes into plant and animal material to break down the

organic compounds, starting with compounds such as sugars

which are easily broken down, and ending with more resis-

tant compounds such as cellulose and lignin. Rates of decom-

position are faster at higher values of moisture and tempera-

ture. Decomposers thus perform a unique and important

function in the

recycling

process in nature.

Decomposition

The chemical and biochemical breakdown of a complex

substance into its constituent compounds and elements, re-

leasing energy, and often with the formation of new, simpler

substances. Organic decomposition takes place mostly in or

on the

soil

under

aerobic

conditions. Dead plant and animal

materials are consumed by a myriad of organisms, from mice

and moles, to worms and beetles, to

fungi

and bacteria.

Enzymes produced by these organisms attack the decaying

material, releasing water,

carbon dioxide

, nutrients,

hu-

mus

, and heat. New microbial cells are created in the process.

Decomposition is a major process in

nutrient

cycling,

including the

carbon

and

nitrogen

cycles. The liberated

carbon dioxide can be absorbed by photosynthetic organisms,

including green plants, and made into new tissue in the

photosynthesis

process, or it can be used as a carbon source

by autotrophic organisms.

Decomposition also acts on inorganic substances in a

process called

weathering

. Minerals broken free from rocks

by physical disintegration can chemically decompose by re-

acting with water and other

chemicals

to release elements,

including potassium, calcium, magnesium, and iron. These

and other elements can be taken up by plants and

microor-

ganisms

, or they can remain in the soil system to react with

other constituents, forming clays.

Deep ecology

The term “deep ecology’ was coined by the Norwegian envi-

ronmental philosopher Arne Naess in 1973. Naess drew a

distinction between “shallow” and “deep”

ecology

. The for-

mer perspective stresses the desirability of conserving

natu-

ral resources

, reducing levels of air and

water pollution

and other policies primarily for promoting the health and

welfare of human beings. Deep ecologists maintain that

shallow ecology simply accepts, uncritically and without re-

flection, the homocentric, or human-centered, view that hu-

mans are, or ought to be, if not the masters of

nature

, then

at least the managers of nature for human ends or purposes.

355

Defenders of deep ecology, by contrast, claim that shallow

environmentalism

is defective in placing human interests

above those of animals and ecosystems. Human beings, like

all lower creatures, exist within complex webs of interaction

and interdependency. If people insist on conquering, domi-

nating, or merely managing nature for their own benefit or

amusement, if people fail to recognize and appreciate the

complex webs that hold and sustain them, they will degrade

and eventually destroy the natural

environment

that sustains

all life.

But, deep ecologists say, if people are to protect the

environment for all

species

, now and in the future, they

must challenge and change long-held basic beliefs and atti-

tudes about our species place in nature. For example, people

must recognize that animals, plants, and the ecosystems that

sustain them have intrinsic value—that is, are valuable in

and of themselves—quite apart from any use or instrumental

value they might have for human beings. The genetic diver-

sity found in insects and plants in tropical rain forests is to

be protected not (only or merely) because it might one day

yield a drug for curing

cancer

, but also and more importantly

because such

biodiversity

is valuable in its own right. Like-

wise, rivers and lakes should contain clean water not just

because humans need uncontaminated water for swimming

and drinking, but also because fish do. Like Gandhi, to

whom they often refer, deep ecologists teach respect for all

forms of life and the conditions that sustain them.

Critics complain that deep ecologists do not suffi-

ciently respect human life and the conditions that promote

prosperity and other human interests. Some go so far as to

claim that they believe in the moral equivalence of human

and all other life-forms. Thus, say the critics, deep ecologists

would assign equal value to the life of a disease-bearing

mosquito and the child it is about to bite. No human has

the right to swat or spray an insect, to kill pests or predators,

and so on. But in fact this is a caricature of the stance taken

by deep ecology. All creatures, including humans, have the

right to protect themselves from harm, even if that means

depriving a mosquito of a meal or even eliminating it alto-

gether.

Competition

within and among species is normal,

natural, and inevitable.

Bats

eat mosquitoes; bigger fish eat

smaller fish; humans eat big fish; and so on. But for one

species to dominate or destroy all others is neither natural

nor sustainable. Yet human beings have, through technology,

an ever-increasing power to destroy entire ecosystems and

the life that they sustain. Deep ecologists hold that this

power has corrupted human beings and has led them to

think—quite mistakenly—that human purposes are para-

mount and that human interests take precedence over those

of lower or lesser species. Human beings cannot exist inde-

pendently from, but only interdependently with nature’s

myriad species. Once people recognize the depth and degree

Environmental Encyclopedia 3

Deep-well injection

of this interdependence, deep ecologists say, they will learn

humility and respect. The human species’ proper place is

not on top, but within nature and with nature’s creatures

and the conditions that nurture all.

Some cultures and religions have long taught these

lessons. Zen Buddhism, Native American religions, and

other nature-centered belief systems of belief have counseled

humility toward, and respect for, nature and nonhuman

creatures. But the dominant Western reaction is to dismiss

these teachings as primitive or mystical. Deep ecologists, by

contrast, contend that considerable wisdom is to be found

in these native and non-Western perspectives.

Deep ecology is at present a philosophical perspective

within the environmental movement, and not a movement

in itself. This perspective does, however, inform and influ-

ence the actions of some radical environmentalists. Organi-

zations such as

Earth First!

and the

Sea Shepherd Conser-

vation Society

are highly critical of moderate shallow

environmental groups which are prepared to compromise

with loggers, developers, dam builders, strip miners, and oil

companies, thus putting the economic interests of some

human beings ahead of all others. Such development destroys

habitat

, endangers entire species of animals and plants, and

proceeds on the assumption that nature has no

intrinsic

value

, but only instrumental value for human beings. It is

this assumption, and the actions that proceed from it, that

deep ecology is questioning and attempting to change. See

also Ecosophy; Environmental ethics; Foreman, Dave;

Green politics; Greens; Strip mining

[Terence Ball]

ESOURCES

OOKS

Devall, B., and G. Sessions. Deep Ecology: Living as if Nature Mattered.

Salt Lake City, UT: Gibbs M. Smith, 1985.

Foreman, D. Confessions of an Eco-Warrior. New York: Harmony Books,

1991.

Fox, Warwick. Toward a transpersonal Ecology: Developing New Foundations

for Environmentalism. Albany, NY: State University of New York Press,

1995.

Seed, J., J. Macy, P. Fleming, and A. Naess. Thinking Like a Mountain.

Philadelphia, PA: New Society Publishers, 1988.

ERIODICALS

Naess, A. “The Shallow and the Deep, Long-Range Ecology Movement,”

Inquiry 16 (1973): 95-100.

Deep-well injection

Injection of liquid wastes into subsurface geologic formations

is a technology that has been widely adopted as a waste-

disposal practice. The practice entails drilling a well to a

356

permeable

, saline-bearing geologic formation that is con-

fined above and below with impermeable layers known as

confining beds. When the injection zones lie below drinking

water sources at depths typically between 2,000–5,000 ft

(610–1,525 m), they are referred to as Class I disposal

wells

The liquid

hazardous waste

is injected at a pressure that

is sufficient to replace the native fluid and yet not so high

that the integrity of the well and confining beds is at risk.

Injection pressure is a limiting factor because excessive pres-

sure can cause hydraulic fracturing of the injection zone and

confining strata, and the intake rate of most injection wells

is less than 400 gal (1,500 l) per minute.

Deep-well injection of liquid waste is one of the least

expensive methods of

waste management

because little

waste treatment occurs prior to injection. Suspended solids

must be removed from

wastewater

prior to injection to

prevent them from plugging the pores and reducing perme-

ability of the injection zone. Physical and chemical character-

istics of the wastewater must be considered in evaluating its

suitability for disposal by injection.

The principal means of monitoring the wastewater

injection process is recording the flow rate, the injection and

annulus pressures, and the physical and chemical characteris-

tics of the waste. Many consider this inadequate and moni-

toring is still a controversial subject. The major question

which arises concerns the placement of monitoring wells

and whether they increase the risk that wastewater will mi-

grate out of the injection zone if they are improperly con-

structed.

Deep-well injection of wastes began as early as the

1950s, and it was then accepted as a means of alleviating

surface

water pollution

. Today, most injection wells are

located along the Gulf Coast and near the

Great Lakes

and their biggest users are the

petrochemical

, pharmaceuti-

cal, and steel mill industries.

As with all injection wells, there is a concern that the

waste will migrate from the injection zone to the overlying

aquifers. See also Aquifer restoration; Groundwater monitor-

ing; Groundwater pollution; Hazardous waste siting; Haz-

ardous waste site remediation; Water quality

[Milovan S. Beljin]

ESOURCES

OOKS

Assessing the Geochemical Fate of Deep-Well-Injected Hazardous Wastes: Sum-

maries of Recent Research. Washington, DC: U. S. Environmental Protection

Agency, 1990.

THER

International Symposium on Subsurface Injection of Liquid Wastes. Pro-

ceedings of the International Symposium on Subsurface Injection of Liquid Waste.

March 3-5, 1986. Dublin, OH: National Water Well Association, 1986.