The Ecology Book

249

See also: Endangered habitats 236–239 ■ Pesticides 242–247 ■ Deforestation

254–259 ■ Depletion of natural resources 262–265 ■ Ocean acidification 281

THE HUMAN FACTOR

Spreading through the lower

atmosphere, these gases react with

water to produce dilute sulfuric

acid (H 2 SO 4 ) and nitric acid (HNO 3 ).

These weak acids fall as rain and

enter rivers and lakes, making them

more acidic. Increased acidity

stresses animals and plants. Water

snails disappear, fish eggs fail to

hatch, and insects and the frogs

that eat them die. Eventually, lakes

will not support any life.

By the early 1970s, thousands of

lakes in Scandinavia had lost their

fish and were virtually dead. By 1984,

Brooktrout Lake and others in the

Adirondack Mountains, New York,

were devoid of fish. Acid rain also

leaches harmful aluminum from the

soil, and acidic clouds and fog harm

plants, reducing their ability to

photosynthesize, leading to death.

Emission control

In the 1970s and 1980s, other areas

badly affected by acid rain

included the “Black Triangle” of

Czechoslovakia, Germany, and

Poland, where large areas of forest

died. Thanks to Likens’s work,

stricter controls were brought in

after 1990. Scrubber systems that

extract SO 2 were fitted to power

station chimneys with great

success. Emissions of the gas were

cut by almost half in the US, and by

two thirds in Europe. Fish began to

return to lakes and rivers. However,

the problem of acid rain still blights

parts of Russia, China, and India. ■

Fossil fuels burned

by industry emit

sulfur dioxide and

nitrogen oxides

into the air.

The acids fall as rain

into lakes and rivers,

affecting the pH balance

of the water.

These gases react

with water in the

lower atmosphere to

produce sulfuric acid

and nitric acid.

Plants and

animals

cannot live in

the acidic water

and die off.

Gene Likens

Likens was born in Indiana

in 1935. After earning a Ph.D.

in zoology from University of

Wisconsin, he was appointed

assistant professor at

Dartmouth College. In 1963,

with fellow scientists F.

Herbert Bormann, Noye

Johnson, and Robert Pierce, he

began research into the water,

minerals, and life forms in the

Hubbard Brook basin. In

1968, his studies recorded

the widespread prevalence

of acid rain, the product of

emissions from factories in the

Midwest. The team’s work in

the area over many years was

described as one of the world’s

most thorough studies of how

air pollution and land use has

shaped a drainage basin.

Likens’s work on deforestation,

land use, and sustainability

led to a change in policy by

the US Forestry Service. It also

helped shape the amended

Clean Air Act in 1990. Likens

was awarded the National

Medal of Science in 2001.

Key works

1985 An Ecosystem Approach

to Aquatic Ecology: Mirror

Lake and its Environment

1991 Limnological Analyses

We experienced eight

years of denial, but

that’s not unusual in

environmental issues.

Gene Likens

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