A precipitate is a substance to be deposited in solid form from a solution. Besides solid particulate matter, like dust, soot and asbestos, air pollutants include various oxides that are produced by burning fossil fuels, and they can interact with water in the atmosphere to produce acid precipitation.
Nitrogen oxide, carbon oxides, and sulfur oxides all can contribute to the formation of acid precipitation. Acid precipitation can be hazardous to the environment because it can change the delicate balance of pH in an area and can harm fish in lakes and streams along with forest vegetation. A change in pH, where the acidity of water is increased can reduce certain nutrients like calcium. This can affect the food webs in this ecosystem.
Acidification can lead to higher than normal levels of aluminum which can be toxic to aquatic life. In forests, the pH of soils can decrease, which may kill off species that are not adapted to this acidified soil. Also, damage to needles and leaves of trees weakens them and makes them vulnerable to disease.
Acid rain also deposits nitrates, which help plants grow. However, any excess nitrates may not be able to be used fast enough, and as the levels increase, additional amounts of calcium and magnesium are removed from soil, which effects the chemistry of the forest and other ecosystems near by. For example, excess nitrates cause ponds and lakes to become over fertilized in a process called eutrophication. This leads to excess growth of algae; eventually, water quality decreases as algae die, bacteria increase, oxygen becomes depleted and fish die.
Fine particles of sulfate and nitrate ions can affect people's lungs, especially those with asthma and bronchitis. There are two types of acid deposition: wet deposition, including sulfuric and nitric acids, present in precipitation and dry, including sulfuric acid and nitric acid, containing particles that settle out of the air.