Acid rain describes any form of precipitation with
high levels of nitric and sulfuric acids. It can also occur in the form of
snow, fog, and tiny bits of dry material that settle to Earth. (http://environment.nationalgeographic.co.uk/environment/global-warming/acid-rain-overview/)
Rotting vegetation and erupting volcanoes release some
chemicals that can cause acid rain, but most acid rain falls because of human
activities. The biggest culprit is the burning of fossil fuels by coal-burning
power plants, factories, and automobiles.
When humans burn fossil fuels, sulfur dioxide (SO2) and nitrogen oxides (NOx)
are released into the atmosphere. These chemical gases react with water,
oxygen, and other substances to form mild solutions of sulfuric and nitric
acid. Winds may spread these acidic solutions across the atmosphere and over
hundreds of miles. When acid rain reaches Earth, it flows across the surface in
runoff water, enters water systems, and sinks into the soil.
Acid rain has many ecological effects, but none is greater than its impact on
lakes, streams, wetlands, and other aquatic environments. Acid rain makes
waters acidic and causes them to absorb the aluminum that makes its way from
soil into lakes and streams. This combination makes waters toxic to crayfish,
clams, fish, and other aquatic animals.
Some species can tolerate acidic waters better than others.
However, in an interconnected ecosystem, what impacts some species eventually
impacts many more throughout the food chain—including non-aquatic species such
as birds.
Acid rain also damages forests, especially those at higher elevations.
It robs the soil of essential nutrients and releases aluminum in the soil,
which makes it hard for trees to take up water. Trees' leaves and needles are also harmed by
acids.
The effects of acid rain, combined with other environmental stressors, leave
trees and plants less able to withstand cold temperatures, insects, and
disease. The pollutants may also inhibit trees' ability to reproduce. Some
soils are better able to neutralize acids than others. In areas where the
soil's "buffering capacity" is low, the harmful effects of acid rain
are much greater.
The only way to fight acid rain is by curbing the release of the pollutants
that cause it. This means burning fewer fossil fuels. Many governments have
tried to curb emissions by cleaning up industry smokestacks and promoting
alternative fuel sources. These efforts have met with mixed results. But even
if acid rain could be stopped today, it would still take many years for
its harmful effects to disappear.
Individuals can also help prevent acid rain by conserving energy. The less
electricity people use in their homes, the fewer chemicals power plants will
emit. Vehicles are also major fossil fuel users, so drivers can reduce
emissions by using public transportation, carpooling, biking, or simply walking
wherever possible.
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