These chemicals result from the burning of coal to produce electricity, non-ferrous metal smelting and, to a lesser extent, fuel combustion in vehicles. Once these pollutants are released into the atmosphere, they can be converted into secondary chemical pollutants such as nitric acid and sulfuric acid. Both of these pollutants are easily dissolved in water and result in acidic water in the form of rain, snow, sleet and fog. Acidic pollutants also exist as drops of dry acid and as gases. In this gaseous state they can be deposited dry.
Dry deposits produce the same damage as wet deposits.
As rivers, lakes and streams become more acidic they lose their ability to sustain fish and other aquatic life. In extreme cases, whole lakes or steams can become lifeless, except for algae. Acid rain also has a significant affect on the food chain. For example, terrestrial animals depend on aquatic organisms for nourishment and nutrients and are affected as food sources decline or are eliminated. There are multiple pollutant stresses on vegetation and crops.