Nitrogen oxides () and sulfur dioxide () create acid rain by reacting with oxygen and water in the atmosphere to form nitric acid and sulfuric acid. These acids dissolve in cloud droplets and reach the surface through precipitation.
Nitrogen oxides () and sulfur dioxide () create acid rain by reacting with oxygen and water in the atmosphere to form nitric acid and sulfuric acid. These acids dissolve in cloud droplets and reach the surface through precipitation.
This is core SL and HL content in 8.3 Urban air pollution.
Fossil-fuel combustion releases primary pollutants into the atmosphere. High-temperature combustion in vehicle engines and power stations produces , while burning sulfur-containing coal and oil releases .
| Pollutant | Simplified atmospheric pathway | Acid formed |
|---|---|---|
| Nitrogen oxides | Nitric acid, | |
| Sulfur dioxide | , followed by |
These reactions involve the chemical transformation of primary pollutants into secondary pollutants. When nitric and sulfuric acids dissolve in rain, snow, mist, or cloud water, they cause wet deposition. Acidic gases and particles can also settle directly as dry deposition.
Acid deposition lowers the pH of soils and lakes. It can leach mineral nutrients, release toxic aluminium ions into water, damage plant tissues, reduce aquatic biodiversity, irritate human respiratory systems, and chemically weather limestone buildings.
Management targets emissions before deposition occurs. Catalytic converters reduce vehicle nitrogen oxide emissions, while flue-gas desulfurization removes sulfur dioxide from power-station exhausts; low-sulfur fuels and renewable energy reduce both sources. Costs may concern industries, but benefits extend to downwind communities that did not produce the pollution.
A common misconception is that acid rain falls only near its emission source. In reality, prevailing winds can transport and across national borders. Historically, emissions from the United Kingdom and continental Europe contributed to acidification in Scandinavian lakes, making acid rain a transboundary pollution issue requiring international cooperation.
For an explain question, link each stage clearly: fossil-fuel combustion, pollutant emission, atmospheric oxidation, acid formation, deposition, and environmental impact. Do not merely state that and “mix with rain,” and do not confuse acid rain with climate change.
| Sulfuric acid, |