Acid rain refers to precipitation, both wet and dry, that is acidic in nature. Precipitation like sleet, rain, snow or dry acidic components that have a pH of less than 4.0 is termed as acid rain. This phenomenon is the result of industrial and vehicular emissions of sulfur dioxide and nitrogen oxides reacting in the Earth's atmosphere.
Causes and Problems
Acid rain is associated with atmospheric pollution. Today, a myriad of highly deleterious environmental effects are being researched upon. The occurrence results in a precipitous pH value of around 4.0. Every subsequent decrease in the pH value is indicative of a greater acidic composition. Acid rain with pH readings well below 2.4 are being reported consistently from industrialized areas, initiating the need for the development of smokestacks. The acidification is largely triggered by the increased presence of sulfur dioxide in the atmosphere. Emissions from the burning of fossil fuel, industry combustion, wildfires, and volcanic eruptions add to the existent quantum of acid-producing gases in the atmosphere. The other causes are emissions from electricity generating plants and motor vehicles.
The harmful gases traverse across hundreds of kilometers before converting into acids, causing widespread ecological damage. It has an adverse impact on our forests, soils, flora and fauna that thrive in various ecosystems, and human health. The phenomenon has eliminated certain life forms completely, while adversely affecting the quality of soil biology and chemistry. Forest cover too has been extensively damaged, while the precipitation continues to threaten human health with the onslaught of premature death and specific particulate health effects. The phenomenon has not spared the inanimate either. It continues to threaten the survival of historical monuments and structures, with the sulfuric acid induced flaking of limestone, marble, sandstone, and granite.
Preventive Measures and Solutions
The effects of acid rain on our ecosystem can be contained with awareness and education on the trigger factors of the phenomenon. Once these are addressed, the devastating effects can be curbed and remedied. Some of the prevention techniques to the problem include the use of Flue Gas Desulfurization or FGD in coal-burning power plants. This helps filter the sulfur-containing gases and neutralize the same from the stack gases to obtain a pH-neutral that can be physically removed with the help of special 'scrubbers'. The pollutants can also be converted into industrial sulfates. Control of automobile nitrogen oxide emissions also helps reduce the onslaught and address the problem with fervency.
The effects on regional flora and fauna is maximum in Scandinavia and Canada. The rate of deposition of the acidic precipitation largely depends on the concentration of acid in the suspended air particles, nature of ecosystem in the region, wind velocity, and exposure to humidity. Acid deposition has led to the destruction of sensitive flora and inhabitants of our freshwater biomes. Long-term acidic deposition on different soil types has resulted in drastic calcium, magnesium, and potassium depletion, affecting quality and quantity of food crops and dependent biological productivity. The researched 'critical load' or the measure of pollution that an ecosystem can tolerate has recently been converted to a study of the 'target load' or the amount of pollution ecologically acceptable. Research reveals that acidic rain is also a stress trigger generated from issues such as a depleting ozone layer, onslaught of complex diseases, and adverse weather conditions.