Glossary
Acid Deposition
The general term for acids falling from the atmosphere to the Earth's surface, encompassing both wet and dry forms.
Example:
After a long period of industrial emissions, the trees in a forest showed signs of damage from acid deposition, even without visible rain.
Acid Precipitation
Specifically refers to acidic rain, snow, or fog, where acids are dissolved in water and fall to the ground.
Example:
A lake in the Adirondacks experienced a significant drop in fish populations due to prolonged acid precipitation making its waters too acidic.
Acidification
The process by which a substance or environment becomes more acidic, typically indicated by a decrease in pH.
Example:
The acidification of ocean waters due to increased CO2 absorption poses a threat to coral reefs and shellfish.
Dry Deposition
The process where acidic gases (NOx, SO2) and particulates (nitric salts, sulfates) fall directly from the atmosphere to the Earth's surface without precipitation.
Example:
Dust on car surfaces in polluted areas can be a form of dry deposition, containing acidic compounds that can corrode paint over time.
Long-Distance Travel (of pollutants)
The phenomenon where atmospheric pollutants, like those causing acid deposition, are carried by wind patterns far from their original source.
Example:
Industrial emissions from the Midwest United States can contribute to acid rain in the Northeast due to the long-distance travel of pollutants.
Nitric Acid (HNO3)
A strong acid formed in the atmosphere when nitrogen oxides (NOx) react with water and other chemicals.
Example:
Vehicle exhaust contributes to the formation of atmospheric nitric acid, which can then fall as acid rain.
Nitric Salts
Compounds formed when nitrogen oxides react with ammonia gas or other substances in the atmosphere, contributing to dry deposition.
Example:
Fine particulate matter collected from the air near an industrial zone might contain nitric salts, indicating dry acid deposition.
Nitrogen Oxides (NOx)
A group of highly reactive gases containing nitrogen and oxygen, primarily released from vehicle exhaust and burning coal, that contribute to acid deposition.
Example:
Catalytic converters in cars help reduce the emission of nitrogen oxides, a key precursor to smog and acid rain.
Scrubbers
Pollution control technologies installed in industrial facilities, especially power plants, to remove sulfur dioxide (SO2) and other pollutants from exhaust gases.
Example:
Modern coal-fired power plants are often equipped with scrubbers to reduce their environmental impact by capturing harmful emissions.
Sulfates
Compounds formed when sulfur dioxide reacts with ammonia gas or other substances in the atmosphere, contributing to dry deposition.
Example:
The hazy skies over some urban areas can be partly attributed to airborne sulfates from industrial emissions.
Sulfur Dioxide (SO2)
A colorless gas with a pungent odor, primarily released from burning coal and volcanic activity, that is a major precursor to acid deposition.
Example:
Power plants often use scrubbers to remove sulfur dioxide from their exhaust gases before releasing them into the atmosphere.
Sulfuric Acid (H2SO4)
A strong acid formed in the atmosphere when sulfur dioxide (SO2) reacts with water and other chemicals.
Example:
Emissions from coal-fired power plants are a major source of the precursors that form sulfuric acid in the atmosphere.
Wet Deposition
The process where acidic compounds (nitric acid, sulfuric acid) are dissolved in rain, snow, or fog and fall to the Earth's surface.
Example:
A sudden downpour after a period of high air pollution can lead to significant wet deposition, impacting local ecosystems.
pH
A measure of the acidity or alkalinity of a solution, with lower values indicating higher acidity and higher values indicating higher alkalinity.
Example:
When acid rain falls, it can lower the pH of lake water, making it difficult for aquatic organisms to survive.