Environmental Facts: Acid Rain

Hey guys,

I used to imagine acid rain to be a deposition of sulfuric or nitric acid from the skies. Imagine the effect that is going to have on humans, plants, animals and buildings. Burning the skin, corroding metals and basically melting buildings. Scary stuff yeah??? Acid rain is not that intense yet, but with an increasing population explosion, more industrial activities as well as more vehicles on the roads, there has been an increase in the combustion of fossil fuels, which is the predominant cause of acid rain.

Acid rain is a consequence of air pollution. The release of oxides of Carbon, Nitrogen and Sulfur from the combustion of fossil fuels into the atmosphere and the reaction of these gases with water molecules in cloud produce acids. The wet deposition of acidic components in the form of snow, fog and rain as well as the direct dry deposition of acidic particles is generally termed acid rain.

When there is a combustion of any type of fossil fuel, certain gases and particles are released. Sometimes, the particles are visible for example in the combustion of diesel, seen as black sooty particles. Most times however, the gases are not visible but are present. They are present because they are contained as constituents of the fuel. Carbon and sulfur and major of components of fossil fuels and will naturally produce their oxides during burning. Oxides of nitrogen are formed because Nitrogen is abundant in air and combustion usually takes place in the presence of air.

Oxides of Sulfur are also released during volcanic eruptions, therefore areas where some volcanic eruptions have occurred are likely to be affected by acid rain.

The acidity of a substance is measured on a pH scale from 0 - 14. 0 is most acidic and 14 is the most alkaline while 7 is neutral. Strong acids can burn the skin on touch and corrode metals. Rainwater has a pH of 5.7 as a result of the formation of carbonic acid from a reaction between carbon dioxide in air and water molecules. Vinegar and lemon juice have a pH of between 2 - 3, acid rain is usually not as acidic and therefore will not harm human skin. Why worry about acid rain then, you might ask.

Acid rain can be transported over great distances between countries and even continents. In the 1950's when acid rain was discovered, the emission of oxides of carbon, nitrogen and sulfur from industrial processes in Britain was transported to Norway and Scandinavia having the effect of causing fish kills as well as a declining forest ecosystem.

Acid rain forest. Source: Wikispaces.com

This means trees without leaves because essential plant nutrients like potassium and magnesium which help plants to grow are being dissolved in the soil and washed away into lakes and rivers, becoming unavailable for plants use. It also damages plants leaves and affects the ability of plants to photosynthesize normally.

Aquatic environments are also affected because fish and other aquatic organisms function at optimal levels within a certain pH. Eggs hatched by fishes are dissolved because of the increased acidity and cannot hatch properly. Calciferous organisms (organisms with shells) are also affected.

Many buildings and statues that contain calcium carbonate (limestone) are also affected because they react with acids to form salts. The salts are soluble in water and in plain English, the buildings get eroded. This leads to collapse. For statues, the aesthetic and economic values are also lost. 

Effects of acid rain on sculptures. Source:http://www.elmhurst.edu

Reducing the effects of Acid Rain:

To reduce the consequences of acid rain, regulations have been put in place to reduce the levels of sulfur  dioxide emissions from coal combustion using fluidized beds.

Modern cars are being fitted with catalytic converters to reduce the emissions of hydrocarbons and nitrogen oxides during fuel combustion. 

The combustion of fossil fuels is still one of the major ways by which electricity is generated. Alternative  renewable sources of energy such as biomass, wind and solar energy are being researched into to reduce the dependence on fossil fuels.

Governments should provide subsidized alternative forms of transport so that people don't have to always travel by cars.

Walking, cycling and car sharing are individual efforts that can help reduce the amount of gases released into the atmosphere as well as reduce acid rain.

Energy saving approaches such as turning off light switches when they are not in use as well as the use of energy saving appliances can help reduce acid rain.

For forests and aquatic ecosystems, the addition of lime into the soil or rivers and lakes can help neutralize the acidity and prevent the effects of acid rain.