Acid Rain
Is there really such a thing as rain with acid in it?
Yes, acid rain is a very real phenomenon worldwide, and it's been documented since the 1800s, as the Industrial Revolution caused the burning of fossil fuels like coal, gas and oil. When these fuels or any other organic material like wood or paper are burned, they release compounds like sulfur dioxide (SO2) and nitrous oxides (NOx) into the air.
Are SO2 and NOx the causes of acid rain?
Indirectly, yes. When SO2 and NOx enter the atmosphere, they react with water vapor, oxygen and other compounds to form sulfuric acid and nitric acid. This process may take place locally, or -- when winds blow emissions hundreds of miles away -- across international or state boundaries. These acids lower the pH of water condensation in the atmosphere, and when that condensation falls as rain, fog or snow, the resulting acids can wreak havoc on plant and animal life.
(Note: The more acids found in rain, the lower the pH. The pH scale goes from 0 to 14. Values from 0 to 6 are considered acid, 7 is considered neutral, and values from 8 to 14 are considered alkaline. A pH of 1, for example, is far more acidic than a pH of 6.)
What are the effects of acid rain?
The effects of acid rain can vary depending on where it falls and what the local rock and soil is composed of -- an alkaline soil can help buffer the effects of acid rain and reduce its impact on local lakes.
However, when acid rain falls on some soils, the acids can wipe out important microbes and insects that live in soil and leaf litter. When acids from rain and snow enter rivers and lakes, it can kill fish and their eggs -- many fish eggs can't survive at pH lower than 5. This has caused the disappearance of some fish like brook trout from streams in the eastern U.S., where acid rain is more prevalent than in western states. Crayfish, clams, amphibians and other aquatic wildlife are also killed off by acid rain.
What about the effect of acid rain on forests?
Trees
Yes, acid rain is a very real phenomenon worldwide, and it's been documented since the 1800s, as the Industrial Revolution caused the burning of fossil fuels like coal, gas and oil. When these fuels or any other organic material like wood or paper are burned, they release compounds like sulfur dioxide (SO2) and nitrous oxides (NOx) into the air.
Are SO2 and NOx the causes of acid rain?
Indirectly, yes. When SO2 and NOx enter the atmosphere, they react with water vapor, oxygen and other compounds to form sulfuric acid and nitric acid. This process may take place locally, or -- when winds blow emissions hundreds of miles away -- across international or state boundaries. These acids lower the pH of water condensation in the atmosphere, and when that condensation falls as rain, fog or snow, the resulting acids can wreak havoc on plant and animal life.
(Note: The more acids found in rain, the lower the pH. The pH scale goes from 0 to 14. Values from 0 to 6 are considered acid, 7 is considered neutral, and values from 8 to 14 are considered alkaline. A pH of 1, for example, is far more acidic than a pH of 6.)
What are the effects of acid rain?
The effects of acid rain can vary depending on where it falls and what the local rock and soil is composed of -- an alkaline soil can help buffer the effects of acid rain and reduce its impact on local lakes.
However, when acid rain falls on some soils, the acids can wipe out important microbes and insects that live in soil and leaf litter. When acids from rain and snow enter rivers and lakes, it can kill fish and their eggs -- many fish eggs can't survive at pH lower than 5. This has caused the disappearance of some fish like brook trout from streams in the eastern U.S., where acid rain is more prevalent than in western states. Crayfish, clams, amphibians and other aquatic wildlife are also killed off by acid rain.
What about the effect of acid rain on forests?
Trees