Environmental Encyclopedia

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Environmental Encyclopedia 3

Center for Science in the Public Interest

THER

Earth Ethics. Washington, D.C.: Center for the Respect for Life and

Environment.

RGANIZATIONS

Center for Respect of Life and Environment, 2100 L Street, NW,

Washington, D.C. USA 20037 (202) 778-6133, Fax: (202) 778-6138,

Email: info@crle.org, <http://www.crle.org>

Center for Rural Affairs

The Center for Rural Affairs (CRA) is a nonprofit organiza-

tion dedicated to the social, economic and

environmental

health

of rural communities. Founded in 1973, the Center

for Rural Affairs includes among its participants farmers,

ranchers, business people, and educators concerned with the

decline of the family farm.

CRA works to provoke public thought on issues and

government policies that affect rural Americans, especially

in the Midwest and Plains regions of the country. It sponsors

research, education, advocacy, organizing and service proj-

ects aimed to improve the life of rural dwellers. CRA’s

sustainable agriculture

policy is designed to analyze, pro-

pose, and advocate public policies that reward environmental

stewardship, promote family farming, and foster responsible

technology. CRA assists beginning farmers with design and

implement on-site research that helps to make these farms

environmentally sound and economically viable. CRA’s

con-

servation

and education programs address the environmen-

tal problems caused by agricultural practices in the North

Central United States.

Through a rural enterprise assistance program, CRA

teaches rural communities to support self-employment, and

it provides business assistance and revolving loan funds for

the self-employed. It also provides professional farm man-

agement and brokerage service to landowners who are willing

to rent or sell land to beginning farmers. CRA promotes

fair competition in the agriculture marketplace by working

to prevent monopolies, encouraging enforcement of laws

restricting corporate farming in the United States, and advo-

cating for the role of United States farmers in international

markets.

Publications offered by CRA include the Center for

Rural Affairs Newsletter, a monthly report on policy issues

and research findings; the Rural Enterprise Reporter, which

provides information about developing small local enter-

prises; and a variety of special reports on topics such as small

farm technology and business strategy.

[Linda Rehkopf]

227

ESOURCES

RGANIZATIONS

Center for Rural Affairs, 101 S Tallman Street, P.O. Box 406, Walthill, NE

USA 68067 (402) 846-5428, Fax: (402) 846-5420, Email: info@cfra.org,

<http://www.cfra.org>

Center for Science in the Public

Interest

The Center for Science in the Public Interest (CSPI) was

founded in 1971 by Michael Jacobson, who remains its exec-

utive director. It is a consumer advocacy organization princi-

pally concerned with nutrition and food safety, and its mem-

bership consists of scientists, nutrition educators, journalists,

and lawyers.

CSPI has campaigned on a variety of health and nutri-

tion issues, particularly nutritional problems on a national

level. It is the purpose of the group to address “deceptive

marketing practices, dangerous

food additives

or contami-

nants, conflicts of interests in the academic community, and

flawed science propagated by industries concerned solely

with profits.” It monitors current research on nutrition and

food safety, as well as the federal agencies responsible for

these areas. CSPI maintains an office for legal affairs and

special projects. It has initiated legal actions to restrict food

contaminants and to ban food additives that are either unsafe

or poorly tested. The special projects the group has sponsored

include: Americans for Safe Food, the Nutrition Project,

and the Alcohol Policies Project. The center publishes edu-

cational materials on food and nutrition, and it works to

influence policy decisions affecting health and the na-

tional diet.

CSPI has made a significant impact on food marketing

in the past 10 years, and they have successfully contested

food labeling practices in many sectors of the industry. They

were instrumental in forcing fast-food companies to disclose

ingredients, and they have recently pressed the

Food and

Drug Administration

to improve regulations for companies

which make and distribute fruit juice. Many brands do not

reveal the actual percentages of the different juices used to

make them, and certain combinations of juices are often

misleadingly labeled as cherry juice or kiwi juice, for instance,

when they may be little more than a mixture of apple and

grape juice. The organization has also taken action against

deceptive food advertising, particularly advertising for chil-

dren’s products. It has recently demanded further testing of

a sweetener called sucralose, in the wake of studies that have

suggested that it could cause shrinkage of the thymus, a

gland affecting cellular immune responses.

CSPI is funded mainly by foundation grants and sub-

scriptions to its Nutrition Action Newsletter. The newsletter

is published ten months out of the year and is intended to

Environmental Encyclopedia 3

Centers for Disease Control and Prevention

increase public understanding of food safety and nutrition

issues. It frequently examines the consequences of legislation

and regulation at the state and federal level; it has explored

the controversy over organic and chemical farming methods,

and it has studied how agribusiness has changed the way

Americans eat. CSPI also distributes posters, videos, and

computer software, and it offers a directory of mail-order

sources for organically-grown food. Its brochures and reports

include: Guess What’s Coming to Dinner: Contaminants in

Our Food and Organic Agriculture: What the States Are Doing.

It has a staff of 45, a membership of 800,000, and an annual

budget of $10,000,000.

[Douglas Smith]

ESOURCES

RGANIZATIONS

Center for Science in the Public Interest, 1875 Connecticut Ave., NW,

Suite 300, Washington, D.C. USA 20009 (202) 332-9110, Fax: (202)

265-4954, Email: cspi@cspinet.org, <http://www.cspinet.org>

Centers for Disease Control and

Prevention

The Centers for Disease Control and Prevention (CDC) is

the Atlanta, Georgia-based agency of the

Public Health

Service

that has led efforts to prevent diseases such as

ma-

laria

, polio, smallpox, tuberculosis, and acquired immuno-

deficiency syndrome (

AIDS

). As the nation’s prevention

agency, the CDC’s responsibilities have expanded, and it

now addresses contemporary threats to health such as injury,

environmental and occupational hazards, behavioral risks,

and chronic diseases.

Divisions within the CDC use surveillance, epidemio-

logic and laboratory studies, and community interventions

to investigate and prevent public health threats.

The Center for Chronic Disease Prevention and

Health Promotion designs programs to reduce death and

disability from chronic diseases—cardiovascular, kidney,

liver and lung diseases, and

cancer

and diabetes.

The Center for Environmental Health and Injury

Control assists public health officials at the scene of natural

or artificial disasters such as

volcano

eruptions, forest fires,

hazardous

chemical spills

, and nuclear accidents. Scientists

study the effects of

chemicals

and pesticides, reactor acci-

dents, and health threats from

radon

, among others. The

National Institute for Occupational Safety and Health helps

identify chemical and physical hazards that lead to occupa-

tional diseases.

Preventing and controlling infectious diseases has been

a goal of the CDC since its inception in 1946. The Center

for Infectious Diseases investigates outbreaks of infectious

228

disease locally and internationally. The Center for Preven-

tion Services provides financial and technical assistance to

control and prevent diseases. Disease detectives in the

Epide-

miology

Program Office investigate outbreaks around the

world.

Prevention of

tobacco

use is a critical health issue for

CDC because cigarette smoking is the leading preventable

cause of death in this country. The Office on Smoking and

Health conducts research on the effects of smoking, develops

health promotion and education campaigns, and helps health

departments with smoking education programs.

CDC researchers have improved technology for lead

poisoning

screening, particularly in children. CDC evidence

on environmental lead

pollution

was a key in

gasoline

lead

content reduction requirements. The CDC also coordinated

and directed health studies of

Love Canal

, New York, resi-

dents in the 1980s. The director of the CDC administers

the

Agency for Toxic Substances and Disease Registry

the public health agency created to protect the public from

exposure to toxic substances in the

environment

. In 1990,

CDC became responsible for energy-related epidemiologic

research for the

U.S. Department of Energy

nuclear facili-

ties. This includes studies of people who have been exposed

to radiation from materials emitted to the air and water from

plant operations.

The CDC today carries out an ever-widening agenda

with studies on adolescent health, dental disease prevention,

the epidemiology of violence, and categorizing and tracking

birth abnormalities and infant

mortality

[Linda Rehkopf]

ESOURCES

RGANIZATIONS

Centers for Disease Control and Prevention, Public Inquiries/MASO,

Mailstop F07, 1600 Clifton Road, Atlanta, GA USA 30333 Toll Free:

(800) 311-3435, , http://www.cdc.gov

CERCLA

see

Comprehensive Environmental

Response, Compensation, and Liability Act

CERES Principles

see

Valdez Principles

Cesium 137

A radioactive

isotope

of the metallic element cesium. Ce-

sium-137 is one of the major products formed when

ura-

nium

undergoes

nuclear fission

, as in a nuclear reactor or

Environmental Encyclopedia 3

Chaparral

A chain reaction. (Illustration by Laurence Lawson. (Reproduced by permission.)

nuclear weapons

. During atmospheric testing of nuclear

weapons after World War II, cesium-137 was a source of

major concern to health scientists. Researchers found that

the isotope settled to the ground, where it was absorbed by

plants and eaten by animals, ultimately affecting humans.

Once inside the human body, the isotope releases beta parti-

cles, which are carcinogens, teratogens, and mutagens. Large

quantities of cesium-137 were released when the Chernobyl

nuclear reactor exploded in 1986.

CFCs

see

Chlorofluorocarbons

CGIAR

see

Consultative Group on International

Agricultural Research

229

Chain reaction

A situation in which one action causes or initiates a similar

action. In a nuclear chain reaction, for example, a

neutron

strikes a uranium-235 nucleus, causing the nucleus to un-

dergo fission, which in turn produces a variety of products.

Among these products is one or more neutrons. Thus, the

particle needed to initiate this reaction (the neutron) is itself

produced as a result of the reaction. Once begun, the reaction

continues as long as uranium-235 nuclei are available. Nu-

clear chain reactions are important sources of fission and

fusion energy.

Chaparral

Chaparral is an ecological community consisting of drought-

resistant evergreen shrubs and small trees that are adapted

to long, hot, dry summers and mild, rainy winters. The

chaparral is found in five places on earth where there is a

warm land mass and a cool ocean: southern California, the

Environmental Encyclopedia 3

Chelate

Cape Town area of South Africa, the western tip of

Austra-

lia

, the west coast of South America, and the coastal areas

of the Mediterranean in southern Europe. Total annual pre-

cipitation ranges between 15 and 40 inches per year, while

annual temperatures range from 50–64.4 °F (10–18 °C).

Droughts and fires, which are often set by lightning during

the summer/autumn dry season, are common in the chapar-

ral. In fact, because the release of minerals occurs as a result

of fire, many chaparral plants grow best after a fire.

The chaparral may have many types of terrain, includ-

ing flat plains, rocky hills, and mountain slopes. The word

chaparral comes from the Spanish word chaparro, meaning

a dry thicket of oak shrubs.

The plants and animals that live in the chaparral are

adapted to the characteristic hot and dry climatic conditions.

Most of the plants are less than 10 ft tall and have leathery

leaves with thick cuticles that hold moisture. Many of the

shrub

flora

are aromatic, contain flammable oils, and are

adapted to periodic burns. Examples of chaparral plants

include poison oak, scrub oak, pine, manzanita, chamise,

yucca, and cacti. The animals are mainly grassland and

de-

sert

types, including coyotes, jack rabbits, mule deer, rattle-

snakes, mountain lions, kangaroo rats, foxes, bobcats, lizards,

horned toads, praying mantis, honey bees, and ladybugs.

[Judith L. Sims]

ESOURCES

OOKS

Collins, Barbara. Key to Coastal and Chaparral Flowering Plants of Southern

California. Third Edition. Dubuque, IA: Kendall/Hunt Publishing Com-

pany, 2000.

Ricciuti, Edward. R. Chaparral (Biomes of the World. Tarrytown, NY: Bench-

mark Books, 1996.

THER

Collins, Barbara J. Wildflowers of Southern California: Photographs of the

Chaparral. California Lutheran University, February 23, 2002. [cited May

27, 2002]. <http://ww1.clunet.edu/wf/>

Chelate

A chemical compound in which one atom is enclosed within

a larger cluster of atoms that surrounds it like an envelope.

The term comes from the Greek word chela, meaning claw.

Chelating agents—compounds that can form chelates with

other atoms—have a wide variety of environmental applica-

tions. For example, the compound ethylenediaminetetraace-

tic

acid

(EDTA) is used to remove

lead

from the blood.

EDTA molecules surround and bind to lead atoms, and the

chelate is then excreted in the urine. EDTA can also be

used to soften hard water by chelating the calcium and

magnesium ions that cause hardness.

230

Chelyabinsk, Russia

Chelyabinsk is the name of a province and its capital city

in west-central Russia. It covers an area of about 34,000 mi

(88,060 km

) and has a population of about 3.6 million.

Chelyabinsk city lies on the Miass River on the eastern side

of the Ural Mountains. Its population in 1990 was about

1.2 million.

Chelyabinsk is best known today as the home of

Mayak, a 77-mi

(200-km

) complex where

nuclear weap-

ons

were built for the former Soviet Union. Because of

intentional policy decisions and accidental releases of radio-

active materials, Mayak has been called the most polluted

spot on Earth.

Virtually nothing was known about Mayak by the

outside world, the Russian people, or even the residents of

Chelyabinsk themselves until 1991. Then, under the new

philosophy of glasnost, Soviet president Mikhail Gorbachev

released a report on the complex. It listed 937 official cases of

chronic

radiation sickness

among Chelyabinsk residents.

Medical authorities believe that the actual number is many

times larger.

The report also documented the secrecy with which

the Soviet government shrouded its environmental problems

at Mayak. Physicians were not even allowed to discuss the

cause or nature of the radiation sickness. Instead, they had

to refer to it as the “ABC disease.”

Chelyabinsk’s medical problems were apparently the

result of three major “incidents” involving the release of

radiation at Mayak. The first dated from the late 1940s

to the mid-1950s, when

radioactive waste

from nuclear

weapons research and development was dumped directly into

the nearby Techa River. People downstream from Mayak

were exposed to radiation levels 57 times greater than those

at the better-known Chernobyl accident in 1986. The Gor-

bachev report admitted that 28,000 people received radiation

doses of “medical consequence.” Astonishingly, almost no

one was evacuated from the area.

The second incident occurred in 1957, when a nuclear

waste dump at Mayak exploded with a force equivalent to

a five to 10 kiloton atomic bomb. The site had been con-

structed in 1953 as an alternative to simply disgorging radio-

active wastes into the Techa. When the automatic cooling

system failed, materials in the dump were heated to a temper-

ature of 662°F (350°C). In the resulting explosion, 20 million

curies of radiation were released, exposing 270,000 people

to dangerous levels of

radioactivity

. Neither the Soviet

Union nor the United States government, which had de-

tected the accident, revealed the devastation at Mayak.

The third incident happened in 1967. In their search

for ways to dispose of radioactive waste, officials at Mayak

decided in 1951 to use Lake Karachay as a repository. They

Environmental Encyclopedia 3

Chemical oxygen demand

realized that dumping into the Techa was not a satisfactory

solution, and they hoped that Karachay—which has no natu-

ral outlet—would be a better choice.

Unfortunately, radioactive materials began

leaching

into the region’s water supply almost immediately. Radiation

was eventually detected as far as 2 mi (3 km) away. The

1967 disaster occurred when an unusually dry summer di-

minished the lake significantly. A layer of radioactive mate-

rial, deposited on the newly exposed shoreline, was spread

by strong winds that blew across the area. This released

radiation equivalent to the amount contained in the first

atomic bomb explosion over Hiroshima.

[David E. Newton]

ESOURCES

ERIODICALS

Cochran, T. B., and R. S. Norris. “A First Look at the Soviet Bomb

Complex.” Bulletin of the Atomic Scientists 47 (May 1991): 25-31.

Hertsgaard, M. “From Here to Chelyabinsk.” Mother Jones 17 (January-

February 1992): 51-55+.

Perea, J. “Soviet Plutonium Plant ’Killed Thousands’.” New Scientist 134

(20 June 1992): 10.

Wald, M. L. “High Radiation Doses Seen for Soviet Arms Workers.” New

York Times (16 August 1990): A3.

Chemical bond

A chemical bond is any force of attraction between two

atoms strong enough to hold the atoms together for some

period of time. At least five primary types of chemical bonds

are known, ranging from very strong to very weak. They are

covalent, ionic, metallic, and

hydrogen

bonds, and London

forces.

In all cases, a chemical bond ultimately involves forces

of attraction between the positively-charged nucleus of one

atom and the negatively-charged electron of a second atom.

Understanding the nature of chemical bonds has practical

significance since the type of bonding found in a substance

explains to a large extent the macroscopic properties of that

substance.

An ionic bond is one in which one atom completely

loses one or more electrons to a second atom. The first atom

becomes a positively charged

ion

and the second, a negatively

charged ion. The two ions are attracted to each other because

of their opposite electrical charges.

In a covalent bond, two atoms share one or more pairs

of electrons. For example, a hydrogen atom and a fluorine

atom each donate a single electron to form a shared pair

that constitutes a covalent bond between the two atoms.

Both electrons in the shared pair orbit the nuclei of both

atoms.

231

In most cases, covalent and ionic bonding occur in

such a way as to satisfy the Law of Octaves. Essentially that

law states that the most stable configuration for an atom is

one in which the outer energy level of the atom contains

eight electrons or, in the case of smaller atoms, two electrons.

Ionic and covalent bonds might appear to represent

two distinct limits of electron exchange between atoms, one

in which electrons are totally gained and lost (ionic bonding)

and one in which electrons are shared (covalent bonding).

In fact, most chemical bonds fall somewhere between these

two extreme cases. In the hydrogen-fluorine example men-

tioned above, the fluorine nucleus is much larger than the

hydrogen nucleus and, therefore, exerts a greater pull on the

shared electron pair. The electrons spend more time in the

vicinity of the fluorine nucleus and less time in the vicinity

of the hydrogen nucleus. For this reason, the fluorine end

of the bond is more negative than the hydrogen end, and

the bond is said to be a polar covalent bond. A non-polar

covalent bond is possible only between two atoms with equal

attraction for electrons as, for example, between two atoms

of the same element.

Metallic bonds are very different from ionic and cova-

lent bonds in that they involve large numbers of atoms. The

outer electrons of these atoms feel very little attraction to

any one nucleus and are able, therefore, to move freely

throughout the metal.

Hydrogen bonds are very weak forces of attraction

between atoms with partial positive and negative charges.

Hydrogen bonds are especially important in living organisms

since they can be broken and reformed easily during bio-

chemical changes.

London forces are the weakest of chemical bonds.

They are forces of attraction between two uncharged mole-

cules. The force appears to arise from the temporary shift

of electrical charges within each molecule.

[David E. Newton]

ESOURCES

OOKS

Giddings, J. Calvin. Chemistry, Man, and Environmental Change: An Inte-

grated Approach. San Francisco: Canfield Press, 1973.

Chemical oxygen demand

Chemical oxygen demand (COD) is a measure of the ability

of chemical reactions to oxidize matter in an aqueous system.

The results are expressed in terms of oxygen so that they can

be compared directly to the results of

biochemical oxygen

demand

(BOD) testing. The test is performed by adding

the oxidizing solution to a sample, boiling the mixture on

Environmental Encyclopedia 3

Chemical spills

a refluxing apparatus for two hours and then titrating the

amount of dichromate remaining after the refluxing period.

The titration procedure involves adding ferrous ammonium

sulfate (FAS), at a known normality, to reduce the remaining

dichromate. The amount of dichromate reduced during the

test—the initial amount minus the amount remaining at the

end—is then expressed in terms of oxygen. The test has

nothing to do with oxygen initially present or used. It is a

measure of the demand of a solution or suspension for a

strong oxidant. The oxidant will react with most organic

materials and certain inorganic materials under the condi-

tions of the test. For example, Fe

and Mn

will be oxidized

for Fe

and Mn

, respectively, during the test.

Generally, the COD is larger than the BOD exerted

over a five-day period (BOD

), but there are exceptions in

which

microbes

of the BOD test can oxidize materials that

the COD reagents cannot. For a raw, domestic

waste-

water

, the COD/BOD

ratio is in the area of 1.5–3.0/1.0.

Higher ratios would indicate the presence of toxic, non-

biodegradable or less readily

biodegradable

materials.

The COD test is commonly used because it is a rela-

tively short-term, precise test with few interferences. How-

ever, the spent solutions generated by the test are hazardous.

The liquids are acidic, and contain chromium, silver,

mer-

cury

, and perhaps other toxic materials in the sample tested.

For this reason laboratories are doing fewer or smaller COD

tests in which smaller amounts of the same reagents are used.

[Gregory D. Boardman]

ESOURCES

OOKS

Corbitt, R. A. Standard Handbook of Environmental Engineering. New York:

McGraw-Hill, 1990.

Davis, M. L., and D. A. Cornwell. Introduction to Environmental Engi-

neering. New York: McGraw-Hill, 1991.

Peavy, H. S., D. R. Rowe, and G. Tchobanoglous. Environmental Engi-

neering. New York: McGraw-Hill, 1985.

Tchobanoglous, G., and E. D. Schroeder. Water Quality. Reading, MA:

Addison-Wesley, 1985.

Viessman, W., Jr., and M. J. Hammer. Water Supply and Pollution Control.

5th ed. New York: Harper Collins, 1993.

Chemical spills

Chemical spills are any accidental releases of synthetic

chem-

icals

that pose a risk to the

environment

Spills occur at any of the steps between the production

of a chemical and its use. A railroad tank car may spring a

leak; a pipe in a manufacturing plant may break; or an

underground storage tank may corrode allowing its contents

to escape into

groundwater

. These spills are often classified

into four general categories: the release of a substance into

232

a body of water; the release of a liquid on land; the release

of a solid on land; and the release of a gas into the

atmo-

sphere

. The purpose of this method of classification is to

provide the basis for a systematic approach to the control

of any type of chemical spill.

Some of the most famous chemical spills in history illus-

trate these general categories. For example, seven cars of a

train carrying the

pesticide

metam sodium fell off the tracks

near Dunsmuir, California, in August 1991, breaking open

and releasing the chemicals into the Sacramento River. Plant

and aquatic life for 43 mi (70 km) downriver died as a result

of the accident. The pesticide eventually formed a band 225

ft (70 m) wide across Lake Shasta before it could be contained.

In 1983, the

Environmental Protection Agency

(EPA) purchased the whole town of

Times Beach

, Missouri,

and relocated more than 2,200 residents because the land

was so badly contaminated with highly toxic dioxins. The

concentration of these compounds, a by-product of the pro-

duction of herbicides, was more than a thousand times the

maximum recommended level.

In December 1984, a cloud of poisonous gas escaped

from a Union Carbide chemical plant in

Bhopal, India

. The

plant produced the pesticide Sevin from a number of chemi-

cals, many of which were toxic. The gas that accidentally es-

caped probably contained a highly toxic mixture of phosgene,

methyl isocyanate (MIC),

chlorine

carbon monoxide

, and

hydrogen

cyanide, as well as other hazardous gases. The

cloud spread over an area of more than 15 mi

(40 km

exposing more than 200,000 people to its dangers.

Chemists have now developed a sophisticated approach

to the treatment of chemical spills, which involves one or more

of five major steps: containment, physical treatment, chemical

treatment, biological treatment, and disposal or destruction.

Soil

sealants, which can be used to prevent a liquid from sink-

ing into the ground, are an example of containment. One of

the most common methods of physical treatment is activated

charcoal, because it has the ability to adsorb toxic substances

on its surface, thus removing them from the environment.

Chemical treatment is possible because many hazardous ma-

terials in a spill can be treated by adding some other chemical

that will neutralize them, and biological treatment usually in-

volves

microorganisms

that will attack and degrade a toxic

chemical. Open burning,

deep-well injection

, and burial in

landfill

are all methods of ultimate disposal.

[David E. Newton]

ESOURCES

OOKS

Unterberg, W., et al. How to Respond to Hazardous Chemical Spills. Park

Ridge, N.J.: Noyes Data Corporation, 1988.

Environmental Encyclopedia 3

Chemicals

The general public often construes the word “chemical” to

mean a harmful synthetic substance. In fact, however, the

term applies to any element or compound, either natural or

synthetic. The thousands of compounds that make up the

human body are all chemicals, as are the products of scientific

research. A more accurate description, however, can be found

in the dictionary. Thus, aspirin is a chemical by this defini-

tion, since it is the product of a series of chemical reactions.

The story of chemicals began with the rise of human

society. Indeed, early stages of human history, such as the

Iron,

Copper

, and Bronze Ages reflect humans’ ability to

produce important new materials. In the first two eras, peo-

ple learned how to purify and use pure metals. In the third

case, they discovered how to combine two to make an alloy

with distinctive properties.

The history of ancient civilizations is filled with exam-

ples of men and women adapting

natural resources

for

their own uses. Egyptians of the eighteenth dynasty (1700–

1500

B.C.

), for example, knew how to use cobalt compounds

to glaze pottery and glass. They had also developed tech-

niques for making and using a variety of dyes.

Over the next 3,000 years, humans expanded and im-

proved their abilities to manipulate natural chemicals. Then,

in the 1850s, a remarkable breakthrough occurred. A discov-

ery by young British scientist William Henry Perkin led to

the birth of the synthetic chemicals industry.

Perkin’s great discovery came about almost by accident,

an occurrence that was to become common in the synthetics

industry. As an 18-year-old student at England’s Royal Col-

lege of Chemistry, Perkin was looking for an artificial com-

pound that could be used as a quinine substitute. Quinine,

the only drug available for the treatment of

malaria

, was

itself in short supply.

Following his teacher’s lead, Perkin carried out a num-

ber of experiments with compounds extracted from

coal

tar,

the black, sticky

sludge

obtained when coal is heated in

insufficient air. Eventually, he produced a black powder

which, when dissolved in alcohol, created a beautiful purple

liquid. Struck by the colorful solution, Perkin tried dyeing

clothes with it.

His efforts were eventually successful. He went on to

mass produce the synthetic dye—mauve, as it was named—

and to create an entirely new industry. The years that fol-

lowed are sometimes referred to as The Mauve Decade

because of the many new synthetic products inspired by

Perkin’s achievement. Some of the great chemists of that

era have been memorialized in the names of the products

they developed or the companies they established: Adolf von

Baeyer (Bayer aspirin), Leo Baekeland (Baekelite plastic),

Eleuthe

re Ire

e du Pont (DuPont Chemical), George East-

233

man (Eastman 910 adhesive and the Eastman Kodak Com-

pany), and Charles Goodyear (Goodyear

Rubber

Chemists soon learned that from the gooey, ugly by-

products of coal tar, a whole host of new products could be

made. Among these products were dyes, medicines, fibers,

flavorings,

plastics

, explosives, and

detergents

. They found

that the other fossil fuels—petroleum and natural gas—could

also produce synthetic chemicals.

Today, synthetic chemicals permeate our lives. They

are at least as much a part of the

environment

, if not more,

than are natural chemicals. They make life healthier, safer,

and more enjoyable. People concerned about the abundance

of “chemicals” in our environment should remember that

everyone benefits from anti-cancer drugs, pain-killing anes-

thetics, long-lasting fibers, vivid dyes, sturdy synthetic rubber

tires, and dozens of other products. The world would be a

much poorer place without them.

Unfortunately, the production, use, and disposal of

synthetic chemicals can create problems because they may

be persistent and/or hazardous. Persistent means that a sub-

stance remains in the environment for a long time: dozens,

hundreds, or thousands of years in many cases. Natural prod-

ucts such as wood and paper degrade naturally as they are

consumed by

microorganisms

. Synthetic chemicals, how-

ever, have not been around long enough for such microor-

ganisms to evolve.

This leads to the familiar problem of

solid waste

disposal. Plastics used for bottles, wrappings, containers, and

hundreds of other purposes do not decay. As a result, landfills

become crowded and communities need new places to dump

their trash.

Persistence is even more of a problem if a chemical

is hazardous. Some chemicals are a problem, for example,

because they are flammable. More commonly, however, a

hazardous chemical will adversely affect the health of a plant

or animal. It may be (1) toxic, (2) carcinogenic, (3) terato-

genic, or (4) mutagenic.

Toxic chemicals cause people, animals, or plants to

become ill, develop a disease, or die. DDT,

chlordane

heptachlor, and aldrin are familiar, toxic pesticides. Carcino-

gens cause

cancer

; teratogens produce

birth defects

. Muta-

gens, perhaps the most sinister of all, inflict genetic damage.

Determining these effects can often be very difficult.

Scientists can usually determine if a chemical will harm or

kill a person. But how does one determine if a chemical

causes cancer twenty years after exposure, is responsible for

birth defects, or produces genetic disorders? After all, any

number of factors may have been responsible for each of

these health problems.

As a result, labeling any specific chemical as carcino-

genic, teratogenic, or mutagenic can be difficult. Still, envi-

Environmental Encyclopedia 3

Chemosynthesis

ronmental scientists have prepared a list of synthetic chemi-

cals that they believe fall into these categories. Among them

are

vinyl chloride

, trichloroethylene,

tetrachloroethylene

the nitrosamines, and chlordane and heptachlor.

Another class of chemicals are hazardous because they

may contribute to the

greenhouse effect

and

ozone layer

depletion

. The single most important chemical in determin-

ing the earth’s annual average temperature is a naturally-

occurring compound,

carbon dioxide

. Its increased produc-

tion is believed to be responsible for a gradual increase in

the planet’s annual average temperature.

But synthetic compounds may also play a role in global

warming.

Chlorofluorocarbons

(CFCs) are widely used in

industry because of their many desirable properties, one of

which is their chemical

stability

. This very property means,

however, that when released into the

atmosphere

, they

remain there for many years. Since they capture heat radiated

from the earth in much the way

carbon

dioxide does, they

are probably important contributors to global warming.

These same chemicals, highly unreactive on earth, de-

compose easily in the upper atmosphere. When they do so,

they react with the

ozone

in the

stratosphere

, converting

it to ordinary oxygen. This may have serious consequences,

since stratospheric ozone shields the earth from harmful

ultraviolet radiation

There are two ways to deal with potentially hazardous

chemicals in the environment. One is to take political or

legal action to reduce the production, limit the use, and/or

control the disposal of such products. A treaty negotiated

and signed in Montreal by more than forty nations in 1987,

for example, calls for a gradual ban on CFC production. If

the treaty is honored, these chemicals will eventually be

phased out of use.

A second approach is to solve the problem scientifi-

cally. Synthetic chemicals are a product of scientific research,

and science can often solve the problems these chemicals

produce. For example, scientists are exploring the possibility

of replacing CFCs with related compounds called fluorocar-

bons (FCs) or hydrochloroflurocarbons (HCFCs). Both are

commercially appealing, but they have fewer harmful effects

on the environment.

[David E. Newton]

ESOURCES

OOKS

Giddings, J. Calvin. Chemistry, Man, and Environmental Change: An Inte-

grated Approach. San Francisco: Canfield Press, 1973.

Joesten, M. D., et al. World of Chemistry. Philadelphia: Saunders College

Publishing, 1991.

Newton, David E. The Chemical Elements. New York: Franklin Watts, 1994.

234

Chemosynthesis

Chemosynthesis is a metabolic pathway used by some bacte-

ria to synthesize new organic compounds such as carbohy-

drates by using energy derived from the oxidation of inor-

ganic molecules—hydrogen sulfide (H

S) or ammonia

(NH

). Chemosynthesis can occur in environments such as

the deep ocean around

hydrothermal vents

, where sunlight

does not penetrate, but where

chemicals

hydrogen

sulfide are available. Chemosynthesis is also a critical part

of the

nitrogen cycle

, where bacteria that live in the

soil

or in special plant structures called heterocysts, utilize ammo-

nia for energy and produce

nitrates and nitrites

which can

subsequently be used as nutrients for plants. Some bacteria

can also utilize hydrogen gas (H

) and

carbon dioxide

(CO

) in a chemosynthetic pathway that results in the pro-

duction of new organic compounds and

methane

(CH

[Marie H. Bundy]

Chernobyl nuclear power station

On April 26, 1986, at precisely 1:24

A.M.

, the Chernobyl

nuclear power

plant exploded, releasing large amounts of

radioactivity

into the

environment

. The power station is

located 9 mi (14.5 km) northwest of the town of Chernobyl,

with a population of 12,500, and less than 2 mi (3.2 km)

from the town of Pripyat, which contains 45,000 inhabitants.

The explosion and its aftermath, including the manner in

which the accident was handled, have raised questions about

the safety and future of nuclear power.

The Chernobyl accident resulted from several factors:

flaws in the engineering design, which were compensated

by a strict set of procedures; failure of the plant management

to enforce these procedures; and finally the decision of the

engineers to conduct a risky experiment. They wanted to

test whether the plant’s turbine generator—from its rotating

inertia—could provide enough power to the reactor in case

of a power shutdown. This experiment required discon-

necting the reactor’s emergency core cooling pump and other

safety devices.

The series of critical events, as described by Richard

Mould in Chernobyl, The Real Story, are as follows: At 1:00

A.M.

on April 25, power reduction was started in preparation

for the experiment. At 1:40

A.M.

the reactors’s emergency

core cooling system was turned off. At 11:10

P.M.

power

was further reduced, resulting in a nearly unmanageable

situation. At 1:00

A.M.

on April 26, power was increased in

an attempt to stabilize the reactor; however, cooling pumps

were operating well beyond their rated capacity, causing a

reduction in steam generation and a fall in stream pressure.

By 1:19

A.M.

, the water in the cooling circuit had approached

Environmental Encyclopedia 3

Chernobyl nuclear power station

the boiling point. At 1:23

A.M.

, the operators tried to control

the reaction by manually pushing control rods into the core;

however, the rods did not descend their full length into the

reactor since destruction of the graphite core was already

occurring. In 4.5 seconds, the power level rose two thou-

sandfold. At 1:24

A.M.

, there was an explosion when the hot

reactor fuel elements, lacking enough liquid for cooling,

decomposed the water into

hydrogen

and oxygen. The

generated pressures blew off the 1,000-ton concrete roof of

the reactor, and burning graphite, molten

uranium

, and

radioactive ashes spilled out to the

atmosphere

The explosion that occurred was not a nuclear explo-

sion such as would occur with an atomic bomb but its effects

were just as devastating. In order to put the expulsion of

radioactive material from the Chernobyl reactor into per-

spective, almost 50 tons of fuel went into the atmosphere

plus an additional 70 tons of fuel, and 700 tons of radioactive

reactor graphite settled in the vicinity of the damaged unit.

Some 50 tons of nuclear fuel and 800 tons of reactor graphite

remained in the reactor vault, with the graphite burning up

completely in the next several days after the accident. The

amount of radioactive material that went into the atmosphere

was equivalent to 10 Hiroshima bombs.

Officials at first denied that there had been a serious

accident at the power plant. The government in Moscow

was led to believe for several hours after the explosion and

fire at Chernobyl that the reactor core was still intact. This

delayed the evacuation for a critical period during which

local citizens were exposed to high radiation levels. The

evacuation of Chernobyl and local villages was spread out

over eight days. A total of 135,000 persons were evacuated

from the area, with the major evacuation at Pripyat starting

at 2:00

P.M.

, the day after the explosion. Tests showed that

air, water, and

soil

around the plant had significant contami-

nation. Children, in particular, were a matter of concern and

were evacuated to the southern Ukraine, the Crimea, and

the Black Sea coast.

At the time of the accident, and for several days there-

after, the winds carried the

radioactive waste

to the north.

The radioactive cloud split into two lobes, one spreading

west and then north through Poland, Germany, Belgium,

and Holland, and the other through Sweden and Finland.

By the first of May, the wind direction changed and the

radioactive fallout—at a diminished rate—went south over

the Balkans and then west through Italy. Large areas of

Europe were affected, and many farmers destroyed their

crops for fear of contamination. Forests have been cleared

and large amounts of earth were removed in order to clean

up radioactivity. Plastic film has been laid in some areas in

an effort to contain radioactive dust.

Officially 31 persons were reported to have been killed

at the reactor site by a combination of the explosion and

235

radiation exposure

; another 174 were exposed to high

doses of radiation which resulted in

radiation sickness

and long-term illnesses. The maximum permissible dose of

radiation for a nuclear power operator is 5 roentgens per

year and for the rest of the population, 0.5 roentgens per

year. At the Chernobyl plant, the levels of radiation ranged

from 1,000 to 20,000 roentgens per hour. One British report

estimates that worldwide, the number of persons afflicted

with

cancer

which can be attributed to the Chernobyl acci-

dent will be about 2,300. Others argued that the number

will be much higher. In Minsk, the rate of

leukemia

has

more than doubled from 41 per million in 1985 to 93 per

million in 1990.

Many heroic deeds were reported during this emer-

gency. Fire fighters exposed themselves to deadly radiation

while trying to stop the inferno. Every one eventually died

from radiation exposure. Construction workers volunteered

to entomb the reactor ruins with a massive concrete sarcoph-

agus. Bus drivers risked further exposure by making repeated

trips into contaminated areas in order to evacuate villagers.

Over 600,000 people were involved in the decontamination

and clean up of Chernobyl. The health effects on them from

their exposure are not completely known. The Chernobyl

accident focused international attention on the risks associ-

ated with operating a nuclear reactor for the generation of

power. Public apprehension has forced some governments

to review their own safety procedures and to compare the

operation of their nuclear reactors with Chernobyl’s. In a

review of the Chernobyl accident by the Atomic Energy

Authority of the United Kingdom, an effort was made to

contrast the design of the Chernobyl reactor and manage-

ment procedures with those in practice in the United States

and the United Kingdom.

Three design drawbacks were noted of the Chernobyl

nuclear power plant:

The reactor was intrinsically unstable below 20% power

and never should have been operated in that mode. (U.S.

and UK reactors do not have this design flaw).

The shut-down operating system was inadequate and con-

tributed to the accident rather than terminating it. (U.S.

and UK control systems differ significantly).

There were no controls to prevent the staff from operating

the reactor in the unstable region or preventing the disa-

bling of existing safeguards.

In addition, the Chernobyl management had no effec-

tive watchdog agency to inspect procedures and order closure

of the facility. Also in years prior to the accident there

was a lack of information given the public of prior nuclear

accidents, typical of the press censorship and news manage-

ment occurring in the period before glasnost. The operators

were not adequately trained nor were they themselves fully

aware of prior nuclear power accidents or near accidents

Environmental Encyclopedia 3

Chesapeake Bay

Chernobyl Nuclear Power Station. Lighter areas of the buidling are part of the original structure, while darker

areas are the steel and concrete “sarcophagus” that was added to contain radioactivity leaking from the faulty

reactor. (Corbis-Bettmann. Reproduced by permission.)

which would have made them more sensitive to the dangers

of a runaway reactor system.

Unfortunately in the former Soviet block nations there

are several nuclear reactors that are potentially as hazardous

as Chernobyl but which must continue operation to maintain

power requirements; however, the operational procedures

are under constant review to avoid another accident. Clearly

the Western world will have to assist the former Soviet block

to bring reactor operating equipment and standards up to a

much higher level of safety to avoid a similar and possibly

more disastrous accident.

[Malcolm T. Hepworth]

ESOURCES

OOKS

Feshbach, M., and A. Friendly Jr. Ecocide in the USSR. New York: Basic

Books, 1992.

Fusco, Paul, and Magdalena Caris. Chernobyl Legacy. de.MO, 2001.

Medvedev, G. No Breathing Room: The Aftermath of Chernobyl. New York:

Basic, 1993.

236

Mould, R. E. Chernobyl: The Real Story. New York: Pergamon, 1988.

Chesapeake Bay

The Chesapeake Bay is the largest

estuary

(186 mi [300

km] long) in the United States. The Bay was formed 1500

years ago by the retreat of glaciers and the subsequent sea

level rise that inundated the lower Susquehanna River valley.

The Bay has a

drainage

basin of 64,076 square miles

(166,000 sq km) covering six states and running through

Pennsylvania, Maryland, the District of Columbia, and Vir-

ginia before entering the Atlantic Ocean. While 150 rivers

enter the Bay, a mere eight account for 90% of the freshwater

input, with the Susquehanna alone contributing nearly half.

Chesapeake Bay is a complex system, composed of numerous

habitats and environmental gradients.

Chesapeake Bay’s abundant

natural resources

at-

tracted native Americans, first settling on its shores. The

first European record of the Bay was in 1572 and the area