2. A broad term
referring to a
mixture of wet and
dry deposited
material from the
atmosphere, which
contains higher
than normal
amounts of nitric
and sulphuric acids.
3. Acid rain formation
results from both
natural sources, such
as volcanoes and
decaying
vegetation, and man-
made
sources, primarily
emissions of sulphur
dioxide and nitrogen
oxides resulting from
fossil fuel
combustion.
4. Acid rain occurs
when these gases
react in the
atmosphere with
water, oxygen, and
other chemicals and
form various acidic
compounds. A mild
solution of sulphuric
acid and nitric acid is
created as a result.
5. Wet deposition refers to acidic rain, fog, and
snow. If the acid chemicals in the air are blown
into areas where the weather is wet, the acids
can fall to the ground in the form of either
rain, snow, fog, or mist. When this acidic water
flows over and through the ground, it affects a
variety of plants and animals. The strength of
the effects depends on several
factors, including how acidic the water is; the
chemistry and buffering capacity of the soils
involved; and the types of fish, trees, and other
living things that rely on the water.
6. In areas where the weather is dry, the acid
chemicals may become incorporated into dust
or smoke and fall to the ground through dry
deposition. They stick to the
ground, buildings, homes, cars, and trees. Dry
deposited gases and particles can be washed
from these surfaces by rainstorms, which lead
to increased runoff. This runoff water makes
the resulting mixture more acidic. Around half
of the acidity in the atmosphere falls back to
earth through dry deposition.
7. In the forest, a spring
shower falls through
the trees to the forest
floor below. Some
trickles over the
ground and runs into
streams, rivers, or
lakes, and some of the
water soaks into the
soil. That soil may
neutralise some or all
of the acidity in acid
rainwater. This is
known as buffering
capacity.
8. Differences in soil buffering
capacity are an important
reason why some areas that
receive acid rain show a lot
of damage, while other
areas that receive about the
same amount of acid rain
do not appear to be harmed
at all. The ability of forest
soils to resist, or
buffer, acidity depends on
the thickness and
composition of the soil, as
well as the type of bedrock
beneath the forest floor.
9. Acid rain doesn’t kill
trees directly. Instead
it damages their
leaves, limits the
nutrients available to
them, or exposes them
to toxic substances
slowly released from
the soil. Quite
often, injury or death
of trees is a result of
these effects of acid
rain in combination
with one or more
additional threats.
10. Scientists know that
acidic water dissolves
nutrients and helpful
minerals in the soil and
washes them away
before trees and plants
can use them to grow.
Acid rain causes the
release of substances
that are toxic to trees
and plants, such as
aluminium, into the
soil.
11. Scientists believe that
this combination of
loss of soil nutrients
and increase of toxic
aluminium may be
one way that acid
rain harms trees.
Such substances also
wash away in the
runoff and are also
released from the
soil when the rainfall
is more acidic.
12. However, trees can
be damaged by acid
rain even if the soil is
well buffered. Forests
in high mountain
regions are often
exposed to great
amounts of acid
because they tend to
be surrounded by
acidic clouds and fog
that are more acidic
than rainfall.
13. Scientists believe that
when leaves are
frequently bathed in
this acid
fog, nutrients in their
leaves and needles
are stripped away.
This loss makes trees
more likely to be
damaged by other
environmental
factors, particularly
cold winter weather.
14. Acid rain can harm
other plants in the
same way it harms
trees. Food crops are
not usually affected
by acid rain because
farmers frequently
add fertilisers to the
soil and by doing
this, they replace the
nutrients that have
washed away.
15. In 1983, a survey in Forests at high
West Germany showed altitudes may be
that 34 % of the enshrouded by clouds
country's total forest is or fog for much of the
damaged by air time. The pH of lower
pollution. This cloud droplets may
included about one average 3.6, which is a
half of the famous much lower pH than
Black Forest. the final rain of pH 4.2.
Switzerland has Some of the most
recorded damage to 14 dramatic effects on
% of her forest trees. forests have been
observed in Europe.
