cause and effect

ACID RAIN

Acid rain, also known as acid deposition, is caused by emissions ofsulfur dioxide (SO2) and nitrogen oxides (NOx) from power plants, cars and factories. Natural sources like volcanoes, forest fire and lightning strikes also add to the man-made pollution. SO2 and NOx become acids when they enter the atmosphere and react with water vapor. The resulting sulfuric and nitric acids can fall as wet or dry depositions. Wet deposition is precipitation: acid rain, snow, sleet or fog. Dry deposition falls as acidic particulates or gases

Scientists express the acidity of acid rain using the pH scale. The scale defines a solution's acidity, neutrality or alkalinity based on its concentration of hydrogen ions. Acids have a high concentration of hydrogen ions and a low pH. The scale ranges from zero to 14, with pure water at a neutral 7.0. Most water, however, is not exactly pure. Even clean, normal rain has a pH of about 5.6. This is because it reacts with carbon dioxide in the atmosphere and forms mildly acidic carbonic acid before it becomes rain.

Acid rain has a pH of 5.0 or less. Most acid deposition ranges from pH 4.3 to 5.0 somewhere between the acidity of orange juice and blackcofee. But comparing acid rain to safe, natural acids can be misleading. Even at its weakest, acid rain wrecks ecosystems by stunting sensitive plants and killing delicate aquatic eggs.

CAUSE

Natural causes of acid rain are relatively small compared to those from anthropogenic sources as discussed above. The following are the most common natural causes of acid rain.

1. Volcanic eruptions: The main natural causal agent for acid rain is volcanic emissions. Volcanoes emit acid-producing gases, mainly sulfur, to create higher than normal amounts of acid rain or any other form of precipitation such as fog or snow to an extent of affecting vegetation cover and health of residents within the surrounding.

1.    Decaying vegetation, wildfires, and biological processes: Decaying vegetation, wildfires, and biological processes within the environment also generate the acid rain forming gases. Dimethyl sulfide is a typical example of a major biological contributor to sulfur-containing elements into the atmosphere.

2.    Lightning: Lightning strikes naturally produce nitric oxides that react with water molecules via electrical activity to produce nitric acid, thereby forming acid rain. Lightning is the major natural source of NOx

Man-made or Anthropogenic Causes of Acid Rain

Human activities leading to chemical gas emissions such as sulfur and nitrogen are the primary contributors to acid rain. Factories, power generations facilities, and automobiles are the chief emitters of sulfur and nitrogen gases. Use of coal for electrical power generation is the biggest contributor to gaseous emissions leading to acid rain.

Automobiles and factories also release high scores of gaseous emissions on a daily basis into the air, especially in highly industrialized areas and urban regions with large numbers of car traffic. As a result, these areas experience exceedingly high amounts of acid rain. Let’s look at the details.

1. Combustion of coal and oil

As stated earlier, the principal emissions accountable for acidic depositions in the atmosphere are oxides of nitrogen (NOx) and sulfur dioxide (SO2). Combusting coal and oil emit loads of these gases into the atmosphere. Once in the atmosphere, these compounds react with atmospheric water molecules in the presence of sunlight to form mild sulfuric and nitric acids.

Coal and oil are burned to produce energy to power machinery and are also used for heating, cooking, and lighting. The bottom line is, combustion of these substances releases the core gases responsible for the formation of acid rain.

2. Power plants and manufacturing industries

Contemporary power plants use fuel to generate energy. In the process of energy generation and combustions, sulfur dioxide and nitrogen oxide gases are released into the atmosphere. Manufacturing industries that manufacture cement, refine petroleum, process plastics, produce chemical products and pharmaceuticals or those that produce metals such as steel and aluminum release scores of NOx and SO2 gases into the atmosphere.

A much as these industries use technologies to reduce the emission of NOx and SO2 gases, the pollutants are released in small amounts but continuously for prolonged time periods eventually leading to the formation of acid rain.

3. Automobiles and other vehicles

Another main source of NOx and SO2 emissions are the fuel combustion of trucks, cars, airplanes, and buses. These automobiles release high levels of sulfur and nitrogen gaseous emissions on a daily basis into the atmosphere, mainly in highly industrialized areas and urban areas with large numbers of car traffic. Accordingly, these areas usually experience substantial amounts of acid rains.

The sulfur and nitrogen emissions can also be blown to other regions leading to acid rain formation in other areas away from the emission sources. For instance, it is believed the acid rain in Sweden is influenced by air pollution in Britain.

EFFECT

Acid Rain Can Cause Health Problems in People

Air pollution like sulfur dioxide and nitrogen oxides can cause respiratory diseases, or can make these diseases worse. Respiratory diseases like asthma or chronic bronchitis make it hard for people to breathe. The pollution that causes acid rain can also create tiny particles. When these particles get into people’s lungs, they can cause health problems, or can make existing health problems worse. Also, nitrogen oxides cause ground-level ozone. This ground-level ozone causes respiratory problems, like pneumia and bronchitis, and can even cause permanent lung damage. The health effects that people have to worry about are not caused by the acid rain, but are caused when people breathe in these tiny particles or ozone. Swimming in an acidic lake or walking in an acidic puddle is no more harmful to people than swimming or walking in clean water.

Acid Rain Harms Forests

Acid rain can be extremely harmful to forests. Acid rain that seeps into the ground can dissolve nutrients, such as magnesium and calcium, that trees need to be healthy. Acid rain also causes alumuni to be released into the soil, which makes it difficult for trees to take up water. Trees that are located in mountainous regions at higher elevations, such as spruce or fir trees, are at greater risk because they are exposed to acidic clouds and fog, which contain greater amounts of acid than rain or snow. The acidic clouds and fog strip important nutrients from their leaves and needles