What is acid rain?
In common parlance, acid rain is just what the words man – rainfall that is acidic in nature. However, in scientific terms it has a winder connotation. So, what is acid rain? Any way by which acid falls out of the atmosphere is considered to be acid rain. It can be dry or wet. Acidic gases or particles are referred to as dry deposition, whereas acid rain, snow and fog constitute the wet deposition. Be it particles, snow or gases, they can be termed as acidic if only they have a higher concentration of hydrogen ions (i.e. pH of less than 4) than usual. But what causes acid rain ad what are its effects on our planet? Let’s consider this environmental issue that has become a serious concern for environmentalists the world over.
What causes acid rain?
Sulfur dioxide and oxides of nitrogen are the gases that cause acid rain to form. These gases can rise high above into the atmosphere. Here they combine with water vapor, oxygen and other chemicals to form acid rain.
Human activity is the main cause of acid rain. Burning of fossil fuels is the primary source of these gases. With increase in industrialization and number of vehicles running on the roads, fumes that contain these gases are being added to the atmosphere at such a rate that the excess of these gases can’t be neutralized by natural process. For example, combustion of fossil fuel in vehicles and industries like iron and steel, processing of crude oil and utility factories contribute to more than 70% of the sulfur dioxide that is added to the atmosphere. Almost 75% of oxides of nitrogen are released by similar process. However, natural phenomena like eruption of volcanoes, lightning, forest fires, rotting vegetables and action of bacteria on the soil also release these gases. However, their contribution amounts to less than 10% of the total amount.
Rapid industrialization is the main cause of increase in the incidence of acid rain and precipitation with low pH value is common in industrialized nations. However, an amusing acid rain face is that it need not occur at the same place from where the gases that form acid rain, are released. Sulfur dioxide and oxides of nitrogen are very light and they can be carried far away from the industries that actually spewed them. Hence, acid rain can also be experienced in places that are not heavily industrialized.
Effects of acid rain: acid rain has serious implication for continuation of life on this planet. The main acid rain problems are:
Effects of water Bodies: most rivers and lakes have pH that rangers between 6 and 8. Acid rain that may fall directly in these water bodies or may be washed into them as surface runoff, alter their chemical environment. the flora and fauna in these water bodies are adapted for life in the original pH value of the water. Altered acidity of their environment may be a threat to their survival. Although, some solid are capable of buffering increase in acidity, water bodies that have soil with poor buffering increase in acidity, water bodies that have soil with poor buffering capacity may release aluminum ions from the soil which is toxic for aquatic life forms.
Effects on soil and forests: acid rain is being cited as one of the major causes of degradation of the forest at higher altitudes of the Appalachian Mountains from Maine to Georgia. Forests are affected directly as well as indirectly by acid rain. When leaves are frequently exposed to acid rain they are stripped off the essential nutrients present in them. Acid rain falling on the soil, change soil acidity. In its bid to neutralize this change in pH, soil releases substances that are toxic for trees growing on it. Acidic water also dissolve nutrients in the soil and as it runs off the surface, it carries these essential mineral away with it, before they can be absorbed flora growing on the forest floor.
Effects on Human Beings: in contrast to common misconception, acid rain is not directly harmful to human beings, it feels and tastes just like normal rain and taking a walk out in acid rain won’t have any direct implication on human health. However, the gases, sulfur dioxide and oxides of nitrogen when inhaled, cause heart and lung problems link bronchitis and asthma.
Other than these major effects, acid rain also cause damage to buildings and structure like statues and bridges. The acid present in these rains corrodes the material that these structures are made of. Although natural elements like wind, water and ice also cause erosion of these structures, acid rain hastens this process.
An understanding of what cause acid rain and its effects makes the need to find acid rain solutions even more urgent. The only why that seems possible to do that is to cut down the industrial emission of gases like sulfur dioxide and oxides of nitrogen. This is essential to preserve the delicate balance of nature on which our survival is precariously balanced.