Types

• Sulfur oxides (SOx), nitric oxides (NOx) and carbon dioxide (CO2) are three common pollutants released by power plants and car engines. Carbon dioxide is produced through the combustion reaction where carbon in the fuel combines with oxygen to make CO2, while sulfur-rich fuels like certain types of coal can create sulfur oxides when burned. Nitric oxides form when high temperatures in a combustion chamber like the cylinder in a car cause nitrogen and oxygen to combine to make NO or NO2.
  
  

Effects

• Sulfur oxides can react with water to form sulfurous acid or sulfuric acid; nitric oxides are similar in that they can combine with water to form nitric acid. These acids can decrease the pH of rainwater so that it becomes acidic. As the concentration of CO2 in the atmosphere increases, the amount of CO2 dissolved in seawater will also increase, and the CO2 will react with water to produce a weak acid called carbonic acid, gradually reducing the pH of seawater.
  
  

Significance

• Ocean acidification can destroy coral and other marine organisms that make shells or plates out of calcium carbonate. Acid rain can damage forests, leach minerals from the soil, or acidify streams and lakes, wreaking havoc on ecosystems that provide shelter to countless plants and animals. In urban environments, acid rain can degrade public monuments and stone buildings by eroding vulnerable materials like limestone.