Acid rain is the product of nitric and sulfuric air pollution interacting with water molecules in the atmosphere. The term acid rain, or acidic precipitation refers to the process of wet deposition where any form of precipitation removes acids from the atmosphere in the form of rain or snow that falls to the surface of the Earth. Alternatively, acids in the atmosphere can be present at ground level without any from of wet deposition where they stick to plants, ground formations or man-made structures. This is referred to as dry deposition.
What Does Acid Rain Look Like?
Acidity is measured on the pH scale that ranges from 0 to 14. A chemical with a pH value greater than 7 is known as an alkaline while something under 7 is referred to as acidic. Lemon juice, for example, has a pH of 2.2 making it very acidic. You can’t see acidity in rain or snow but you can test for it with test strips. If you have a well on your property or use a pool you have likely tested for pH values. Note that rain with a pH level above 5.6 is not referred to as acid rain.
Where is Acid Rain a Problem?
The eastern third of the United States where coal consumption is greatest measures higher levels of acidity in rain. Parts of eastern Ohio and western Pennsylvania are particularly noteworthy for registering pH levels of 4.6 and 4.7. Those higher levels compare to areas of Nevada and California where coal consumption is lowest and we see pH levels in rain measuring 6.0. Since these areas measure pH levels above 5.6 the term acid rain does not apply.
Industrial activity alone is not the only source of problematic gases in the atmosphere. Besides automobiles, ships, and planes, bacterial activity, forest fires, and volcanoes can make acid rain more or less of a problem depending on severity of the event.
What Are the Effects of Acid Rain on the Environment?
The term acid rain was coined in the late 1800s. Public awareness of acid rain grew in the 1970s when published studies revealed damage to lakes caused many species of fish to disappear. Research shows that acid rain interferes with a fish’s ability to take in oxygen, salt, and nutrients. The symptoms of fish suffering from these effects can be seen as mucus around gills, eggs that are too brittle, and bone deformities.
There are other problems to consider. High nitrogen content in fertilizer causes algae blooms. Like fish, algae are a living organism that needs oxygen, but in large numbers oxygenation in water drops significantly starving aquatic life in the process. Crayfish, clams, many types of fish, and other aquatic animals are all impacted by the effects of not just algae blooms but metals released from soil when acid rain falls. Due to the sensitivity of the food chain, as fish die off so too do birds and insects.
At higher elevations acid rain and the release of aluminum in soil robs trees of essential nutrients. High acidity washes away the protective coating on leaves affecting their ability to photosynthesis properly. This leaves affected trees often unable to properly take in moisture, develop fully, or survive cold weather.
What Happens When Acid Rain Falls on Limestone?
Many of our favorite statues and buildings are made from limestone and marble. These stone materials are made up of calcite molecules that after interacting with the acidic properties of acid rain turn into calcium sulfate which can be dissolved by water. The effects of acid rain on old statues and buildings is often evident by a loss of fine facial detailing or writing. Some problems might not be immediately visible, with cracks or pieces breaking off occurring suddenly due to weakened stone.
How is human health affected by acid rain?
Particulate matter associated with acid rain can impact those with existing respiratory problems. Otherwise the only real threat comes from unbalanced pH levels that cause corrosion of pipes and household fixtures, however utility companies monitor those levels so they remain between 6.5 and 8.5 on the pH scale.
Any water should be treated and filtered before consumption, but high acidity in water isn’t enough to cause immediate health problem. If the pH levels of your water are outside the recommended levels, steps should be taken to prevent long-term problems.
Don’t worry about playing in the rain, acid rain will not burn your skin.
Can acid rain be prevented?
The severity of acid rain is directly tired to human activity. While acid rain does occurs naturally, the percentage is minimal compared to how the burning of fossil fuels adds pollutants into the atmosphere. Tighter emission controls and sustainable power generation will have the greatest impact on reducing acid rain.