BISL 04-Weather and Climate

86 CLIMATE CHANGE WEATHER AND CLIMATE 87

B

urning fossil fuel releases into the air chemicals that mix with water vapor

and produce acid rain. The excess of sulfur dioxides and nitrogen dioxides in

bodies of water makes the development of aquatic life more difficult,

substantially increasing the mortality rate of fish. Likewise, it affects vegetation on

land, causing significant damage in forested areas by contaminating animals and

destroying substances vital for the soil. Moreover, acidic sedimentation can increase

the levels of toxic metals, such as aluminum, copper, and mercury, that are deposited

in untreated drinking-water reservoirs.

Toxic Rain

LEAVES

This rain damages their

surface, causing small

lesions that alter the

Fir Beech Oak action of photosynthesis.

Areas under cultivation are

not as vulnerable because

they are generally improved

by fertilizers that restore

nutrients to the soil and

neutralize acidity.

Melting water carries

acidic particles that

come from the rain.

Seriously affected

species are lettuce and

tobacco, especially

because their leaves,

destined for human

consumption, must be

of high quality.

Acid rain acts via certain

mechanisms that weaken

plants, making them more

vulnerable to the effects of

wind, cold, drought,

disease, and parasites.

In mountainous areas, fog and

snow contribute significant

quantities of the gases in question.

The acidity of rainwater

changes the neutral pH of

bodies of water.

MOST-THREATENED SPECIES

CONSEQUENCES

FOR PLANTS

CONSEQUENCES

FOR AGRICULTURE

EFFECTS ON

THE WATER

SOIL

CONSEQUENCES

Atmospheric circulation enhances

the dispersal of contaminants

over great distances.

AREAS AFFECTED BY ACID RAIN

WHAT IS pH?

The degree of

acidity of an

aqueous solution.

It indicates the

concentration of

hydrogen ions.

pH

neutral

pH

acid

Destruction

of chlorophyll

Defoliation

1972

The year when the

phenomenon of acid rain was

recorded for the first time

Petroleum

refineries

SILICATE SOIL

The effect of acidity

increases because of the lack

of buffering minerals.

CALCAREOUS SOIL

The effect is neutralized by

the presence of bicarbonate.

Root

damage

The leaves lose

their wax layer.

pH:6

Normal rain

pH:5

Acid rain

pH 7

(neutral)

pH 4.3

(acid)

1

GAS EMISSIONS

Generated by burning fuels

and the eruption of volcanoes

Waste

incinerator

Chemical

industry

CO 2 SO 2 CH 4 H 2 S CO NO 2

4

ACID RAIN

falls in the form of water, fog, or

dew and leaves the acids formed in

the atmosphere on the ground.

The regions most vulnerable to this phenomenon are

Mexico, Beijing, Cairo, Jakarta (Indonesia), and Los

Angeles.

2

GAS MIXTURES

The molecules of various

gases rise and mix with

water in the air.

3

PHOTOCHEMICAL

REACTION

Sunlight increases the speed at

which chemical reactions occur. Thus,

sulfur dioxide and atmospheric gases

rapidly produce sulfur trioxide.

pH 4.3

LEVEL AT WHICH FISH DO

NOT SURVIVE IN THE WATER Trout Perch Frogs

MOST-AFFECTED SPECIES

TYPES OF GASES EMITTED

Chemical

industry

CO 2 , SO 2 ,

H 2 S(hydrogen sulfide)

Waste

incinerator

CO 2 , SO 2 , CH 4 ,

CO(carbon monoxide)

NO 2 (nitrogen dioxide)

CO 2 (carbon dioxide)

SO 2 (sulfur dioxide)

CH 4 (methane)

Petroleum

refinery