When sulfur dioxide and nitrogen oxides, both byproducts of the combustion of fossil fuels like coal, natural gas, and oil for heat or electricity, are released into the atmosphere, they react with water and oxygen to form acids. Specifically, these chemicals give rise to hydrogen sulfide (HS) and nitric acid (HNO3). Both of these substances are known as “acids” because of their ability to neutralize alkalinity in another solution.
In the case of sulfur dioxide reacting with water vapor to create acid rain, it is a weak hydrochloric acid. Acid rain is not a type of rain that you need to avoid getting wet in or anything crazy like that; it’s an uncommon phenomenon that can have a disastrous impact on the environment if left unmitigated. Fortunately, there are several steps you can take as an individual to help mitigate the effects of this phenomenon.
How Does Rain Become Acidic?
We’ll begin this discussion by looking at the composition of rainwater. As you can imagine, the exact percentage of specific compounds will vary depending on the region, season, and even time of day. Rainwater is naturally acidic, with a pH of approximately 5.6.
This is on the low end of the pH scale, which is an indicator of how acidic or alkaline a substance is. A pH of 7 is neutral. A pH below 7 is acidic, and a pH above 7 is alkaline. This means that rainwater is slightly acidic, which isn’t a problem in itself. But, as rainwater comes into contact with certain substances, it can become significantly more acidic.
Types of Acid Rain
Acid rain can be classified mainly into two types: Wet Deposition and Dry Deposition. Wet deposition refers to acid rain that falls from the atmosphere to the ground in the form of rain, snow, or sleet. This type of acid rain is also called precipitation.
Dry deposition refers to acid rain that falls to the ground in the form of gas and dust particles. These particles can be transported by wind and eventually fall to the ground.
How Does Acid Rain Form?
Fossil fuels, such as coal, oil, and natural gas, produce sulfur dioxide and nitrogen dioxide when they are burned. These gases rise into the atmosphere and mix with water vapor to form acids. The acids then fall back to Earth in the form of rain, snow, or fog, a process known as acid deposition.
The result of these chemical reactions is the formation of a solution that is acidic and harmful to humans, animals, and plants. The solution of sulfuric and nitric acids will bring these harmful substances down to the surface level in the form of rain once the air masses that have the chemicals in them are cooled and the water vapor condenses at cooler temperatures.
Natural and Man-made Acid Rain
Natural acid rain is caused by high levels of air pollution and the reaction of water droplets with the pollutants. There are three main causes of natural acid rain: sulfur dioxide, nitrogen oxides, and hydrogen chloride. These pollutants enter the atmosphere and react with water vapor to form sulfuric acid, nitric acid, or hydrochloric acid. The acids then fall to the ground in rain, snow, or fog.
Apart from human activity, other sources like forest fires, volcanoes, and decaying organic matter also produce sulfur dioxide and nitrogen oxides. Although these natural processes have been happening long before industrialization, the rapid increase in emissions from human activity has resulted in a much higher concentration of nitrogen oxides in the atmosphere.
Man-made Acid Rain is caused by human activities. Over the past few decades, humans have released so many different chemicals into the air that they have changed the mix of gases in the atmosphere. Coal and other fossil fuels create a lot of sulfur dioxide and nitrogen oxides when they are burned to produce electricity. Nitrogen oxides and sulfur dioxide are released from the exhaust of cars, trucks, and buses. Acid rain is caused by pollutants.
The Environmental Impact of Acid Rain
As mentioned above, acid rain harms the soil, plants, and animals that live there. Let’s take a look at the impact that acid rain can have on each of these. First of all, acid rain will decrease the nutritional value of plants. This can have particularly adverse effects on crops that are grown in fields. In addition, when acid rain falls on soil, it can cause metal ions, like aluminum, iron, and manganese, to leach into the soil.
This can harm the soil’s pH level, as well as the growth of certain plants that are sensitive to low pH levels. When acid rain falls on the surface of the water, it can cause an increase in the amount of aluminum in the water. This can be harmful to aquatic life that lives near the surface of the water. Acid rain can also cause acidification of surface water, which can lead to an increase in the acidity of groundwater. This can harm the creatures that live in freshwater ecosystems.
In this article, we explored what causes acid rain and its effects on the environment. Rainwater is naturally acidic, with a pH of approximately 5.6. This is on the low end of the pH scale, which is an indicator of how acidic or alkaline a substance is. A pH of 7 is neutral. A pH below 7 is acidic, and a pH above 7 is alkaline.
This means that rainwater is slightly acidic, which isn’t a problem in itself. But, as rainwater comes into contact with certain substances such as sulfur dioxide, it can become significantly more acidic.
When these pollutants mix with water droplets in the air and they are then deposited on the ground as rain. It is most dangerous in areas like Scandinavia because it falls as a fine mist. Buildings and monuments that are made of stone are particularly vulnerable to the effects of acid rain.
There are a number of ways we can reduce pollution, which will help prevent acid rain by decreasing the number of pollutants released into the atmosphere.