Sources of Acid Deposition
The primary emissions responsible for acid deposition are sulfur dioxide (SO2) and oxides of nitrogen (NOx) from the combustion of coal, oil and natural gas. The combustion compounds are transformed into sulfuric and nitric acid and transported downwind before they are deposited.
Some of the conveniences we take for granted everyday also lead to the emissions responsible for acid deposition. The burning of fossil fuels to supply the electricity we use is a source of sulfur dioxide and nitrogen oxides. Another source is the burning of fuels to power cars, trucks, buses and airplanes. However, scientists and engineers are working on new ways to reduce harmful emissions.
Power Plants
Modern power plants use fuel that has had the sulfur reduced before it is burned or the plants use scrubbers in the smokestacks to remove the sulfur from the emissions. NOxemissions are reduced by using specially designed low NOx combustors and selective catalytic reduction (SCR) or non-selective catalytic reduction (NSCR) in the smokestacks.
Automobiles and Other Vehicles
Since the mid-1970s, two important features have been added to automobiles - catalytic converters and electronic fuel injection (EFI). Catalytic converters are located in the exhaust system to remove NOx emissions. EFI controls the formation of NOx emissions during combustion of the fuels. And, starting in 1996, automobiles have been equipped with onboard diagnostics (OBD) that signal the driver when the various components of emission control are not operating properly. Efforts are also being made to reduce the amount of sulfur in vehicle fuels. Cars using low-sulfur fuels not only emit less SO2, but also less NOx, because catalytic converters work more efficiently with low-sulfur fuel.
NEW!!! Go to the NYS Transportation Federation Transportation Status site for the Albany area (link at right).
Each of us can also take part in reducing acid rain. When we turn off a light, we reduce the demand for electricity from power plants. When we car pool, take public transportation, or walk, we reduce automobile emissions. Many small contributions can together make a significant reduction in emissions that lead to acid deposition.
