With Spring flowers on the horizon, people are generally happy about getting rain so that the plants that make up a vibrant Spring are able to grow. However, sometimes this rain can cause more harm than good if it picks up extra contaminants and pollutants before it falls to the ground, turning it into acid rain. Acid rain forms when sulfur dioxides and nitrous oxides are released into the air where they can react with water or oxygen to form sulfuric and nitric acids. Not surprisingly, these acids can cause a lot of damage to the plants and animals that make up various ecosystems across the country.
Like most damage done to the environment, acid rain is largely due to human activity. While some of it can be attributed to decaying vegetation and volcanoes, the large proportion comes from burning fossil fuels. In fact, two thirds of the sulfates in the atmosphere and one quarter of the nitrates come from generating electricity. Other sources include: vehicles, heavy equipment, manufacturing, oil refineries, and various other industries.
Acid rain can form in two different ways: wet deposition and dry deposition. Wet deposition is the traditional “acid rain” where the sulfuric and nitric acids mix with precipitation like rain, snow, or hail. Dry deposition does not initially require any water because the acidic particles can settle onto dry vegetation or structures. When rain does come, it reacts with the settled particles and the runoff becomes acidic, disrupting plant and animal life as the water flows over the ground.
The biggest issue acid rain creates is that is significantly lowers the pH of the water. pH is a measure of the concentration of hydrogen ions in a solution, where pH values less than 7 are acidic and values greater than 7 are basic. The amount of these ions present in the solution can play a big role in what chemical reactions happen or how quickly they occur, and because all life is dependent on systems of chemical reactions, pH has a tremendous impact on living organisms. Most animals and plants have ideal ranges of pH to live in, typically between 6.5 and 8.5, and as pH deviates from this range, survival, hatching, and growth decrease as life processes are put under stress.
The sulfates and nitrates in the acid rain cause the pH to drop from 5.6 to 4.2 or lower. Normal rain starts out fairly acidic because of dissolved carbon dioxide, but aquatic ecosystems are equipped to manage that. They are not, however, able to resist the changes that 4.2 pH rain will bring to the ecosystem. Even a small change in the pH of a body of water can have lasting impacts. For example, it can make other compounds, like phosphorus, more soluble which then promotes the growth of algae that can cause eutrophication, or the gradual death of a pond as dissolved oxygen is depleted.
Acid rain can also wreak havoc on non-aquatic environments since it can affect soil composition because the acid allows for greater aluminum accumulation. This, combined with a drop in calcium levels, prevent plants from properly taking up water through their roots. Acid rain can also damage plant leaves and stems, and even the stress of dealing with acidic solutions makes vegetation more vulnerable to cold temperatures, disease, and insects. Some forests have soil with good “buffering capacity”, or the ability to resist major changes to pH, but most can be severely damaged by acid rain.
One of the largest issues with acid rain is that the original source of the pollutant, the sulfates and nitrates, can be hundreds of miles away from the actual sites affected by acid rain since the pollutants can be carried long distances by wind. The Adirondack Mountain region, for example, has been greatly affected by acid rain originating in the midwest. Air currents brought pollution from Ohio, Illinois, Indiana, etc. to the northeast region of New York, where it came down as acid rain. Because the Adirondack area gets a lot of precipitation and has very little buffering capacity, it was hit extremely hard. In the last hundred years, every 2.5 acres received 3,300 pounds of sulfur, causing 20 to 40% of lakes to become acidified and 10 to 25% highly acidified.
Luckily, there is something that can be done. In the case of the Adirondack Mountains, a lawsuit filed against American Electric Power, a coal-burning company based in Ohio, required the company to implement $4.6 billion pollution control mechanisms while paying $60 million to help restore areas damaged by their pollution and acid rain. Because this is an interstate issue, the federal government needs to get involved, and luckily it did with the Clean Air Act of 1990 that has reduced sulfur dioxide emission by 88% and nitrogen oxides by 50%. While these reductions are good, there will always be acid rain if fossil fuels are used as energy sources. To truly get rid of acid rain, cleaner, renewable energy sources like solar, wind, and water power would need to implemented on a much larger scale across the country.
I read another environmental civic issue blog about acid rain, in which I learned that acid rain doesn’t directly hurt humans. I guess wherever I hear the words “acid rain” it conjures up images of green rain that burns through skin (or something much more extreme like this). Regardless, the indirect effects of acid rain are just as harmful to humans, and, like many of the environmental issues we face, it will take a holistic effort from society. I appreciate that you put such a large focus on the Adirondacks and other regions of the United States that are affected by our emissions. I think too few Americans are aware/care about how their actions affect the environment around them; they focus to much on themselves as humans. I remain pessimistic, however, that our society can work to mitigate issues, like acid rain, which do not directly threaten us.