How has acid rain harmed lakes and forests in North America and Europe?

Acid rain, caused primarily by the emission of sulfur dioxide and nitrogen oxides from fossil-fuel combustion, has significantly impacted ecosystems in North America and Europe.1

Impact on Lakes and Rivers

Acid deposition has acidified tens of thousands of lakes and streams, particularly in regions with low buffering capacity. This acidification mobilizes toxic aluminum from soils into the water, which damages fish gills and impairs respiration. Consequently, many lakes have experienced a dramatic loss of fish populations and overall biodiversity. Additionally, high acidity can accelerate the conversion of mercury into methyl mercury, a potent neurotoxin that bioaccumulates in the food chain.21

Impact on Forests

Forests have suffered from soil acidification, which leaches essential nutrients like calcium and magnesium while mobilizing toxic aluminum. This process weakens trees, making them more susceptible to drought, insects, and pathogens. In the eastern United States, species such as red spruce and sugar maple have shown significant decline due to these chemical changes. While strict air pollution regulations have since reduced acid deposition, many ecosystems remain slow to recover due to long-term soil depletion.314