MODULE VII
Learning Objectives

Issues of concerns in air pollution: green house effect, acid rain, ozone hole, and photochemical smog.

Lecture 1 Lecture 2 Lecture 3 Lecture 4


Acid Rain

What ever happened to acid rain?

  • In the 1980’s, acid rain received a lot of media attention.
  • Although we don’t hear about acid rain as much these days, it is still a problem that deserves our attention.
  • Fortunately, acid rain is a problem that we can all help to solve.

    • What is Acid Rain? How Does it Form?

  • Acid rain” includes both wet and dry acidic deposits
  • Precipitation with a pH lower than 5.6 is considered acidic
  • Acid rain originates from sulfur dioxide and nitrogen oxide particles
  • Once these particles are emitted into the air they form sulfate and nitrate particles
  • These particles can travel long distances on wind currents
  • By combining with water vapor, these particles form acids which fall to the earth as acid rain.

    • The pH Scale

    Measures Potential of Hydrogen
    = total # of free hydrogen

     

    Where do Sulfur Dioxide & Nitrogen Oxide Particles Come From?

  • Sulfur dioxide and nitrogen dioxide particles are emitted from utility plants, especially coal-fed electric plants
  • Automobiles also emit acid rain causing pollution


    • How Does Acid Rain Effect Our Lives?

  • Poor forest health due to acidification of soil: acid rain can kill nutrient-producing microorganisms
  • Acidification of lakes and streams can lead to the death of aquatic life, such as trout and bass
  • Acidity can leach mercury out of the soil, causing toxic levels to build up in the fish we eat
  • Acid rain can erode buildings and monuments and destroy paint finishes

    • What else needs to be done about Acid Rain ?

  • In 1990, an amendment to the Clean Air Act called for reductions in sulfur emissions
  • This proved to be less effective than hoped, as acid rain still persists today
  • This is largely due to 2 reasons:

    • -1) reductions in sulfur emissions were not great enough and
    - 2) there were no reductions in nitrogen emissions which are also implicated in forming acid rain
  • Presently, the New England Governors and eastern Canadian Premieres are working together on a solution
  • An International Acid Rain Steering Committee was formed and is currently discussing joint action to further reduce sulfur emissions by 50% and reduce nitrogen emissions by 30% by the year 2010

    • Can We Do Anything About Acid Rain?

  • YES! We can all take small actions to help solve the problem
  • We can help by:
    -using our cars less
    -conserving electricity
    -choosing electricity providers that emit lower amounts of air pollution emissions