Acid Rain and Geology Acid rain is a term that refers to a mixture of dry and wet deposited materials that falls in precipitation from the atmosphere, containing "higher then normal amounts of nitric and sulfuric acids" (Environmental Protection Agency). Some of the "precursors, or chemical forerunners" of acid rain are from natural sources like volcanoes and rotting vegetation; other precursors are from man-made sources like nitrogen oxides (NOX) and sulfur dioxide (SO2). The man-made emissions result for the most part from the burning of fossil fuels, like coal and oil for electrical production, according to the EPA.

Wet Deposition: In the United States, about two-thirds of all the SO2 and one-quarter of all the NOX results from the burning of coal and oil. Acid rain is created when these gases -- released through the smokestacks of the coal and oil-fired plants -- mix with water and oxygen and other chemical typically found in the air, and rain down on the land, water and forests.

Dry Deposition: Acid rain can be formed in very dry climates when acidic chemicals are mixed in with smoke or dust and fall to the ground, sticking to the ground, trees, buildings and cars, the EPA explains. When rain does fall, the water that runs off becomes even more acidic.

Acid rain creates unnatural amounts of acidification in lakes and rivers and damages trees at higher elevations, the EPA explains. The results tends to accelerate the "decay of building materials and paints" -- and acid rain is unhealthy for trees and humans.

The Literature on Acid Rain and Geology

Acid rain has been impacting the land, forests and waters of some regions of the planet since as early as 1852, according to author S.V.S. Rana in his book, Environmental Pollution: Health and Toxicology. The impact of acid rain isn't entirely determined by the level of acid in the rain, but also on the "nature of the environment itself," Rana writes on page 25. In terms of geology, areas that are underlain by granite or quartatic bedrock...

The reason this is true is that soils and water are already partly acidic, and hence they do not have the ability to "buffer or neutralize additional acidity" from the falling rain (Rana, p. 25). So when acid levels rise in the soil -- soil that is already acidic to a degree -- the environmental balance is "disturbed" and some "serious ecological damage is the inevitable result," Rana makes clear (p. 25).
Meanwhile if the area where acid rain is falling is underlain by chalk or limestone (what Rana calls "geologically basic" areas), that area of oil may well "benefit" from the falling acid rain, Rana continues (p. 25). In areas that feature "highly alkaline soils and water," when the acid rain is added to that environment the acid is "effectively neutralized," according to Rana's book. In areas where there has been "glacial drift" or another "unconsolidated deposit," the susceptibility of the environment to being damaged by acid rain "…will be determined by the nature of the superficial material rather than by the composition of the bedrock" (Rana, p. 25).

Forest Soil and Acid Rain

An article in the journal Communications in Soil Science and Plant Analysis (Kang, et al., 2005, p. 2129) discusses soils and nitrogen in a scholarly context. The authors explain that forest ecosystems are understood to be limited on nitrogen (N) as a general rule, hence productivity can be enhanced with additional nitrogen. However, when excessive amounts of nitrogen are deposited, it can adversely affect the soil, hence the geology. In Europe and North America, as well as the Far Eastern Asia and Korea there is known to be a problem with high levels of nitrogen (due to acid rain) (Kang, 2130).

Once the soil has been saturated with an excess amount of nitrogen, there is the chance that a "nutrient imbalance to vegetation" could occur. Also, with an overabundance of nitrogen in the forest soil (from acid rain) can make trees "vulnerable to frost" -- and places the…