GC: n

CT: The effects of acid rain, combined with other environmental stressors, leave trees and plants less able to withstand cold temperatures, insects, and disease. The pollutants may also inhibit trees’ ability to reproduce. Some soils are better able to neutralize acids than others. In areas where the soil’s “buffering capacity” is low, the harmful effects of acid rain are much greater.
The only way to fight acid rain is by curbing the release of the pollutants that cause it. This means burning fewer fossil fuels. Many governments have tried to curb emissions by cleaning up industry smokestacks and promoting alternative fuel sources. These efforts have met with mixed results. But even if acid rain could be stopped today, it would still take many years for its harmful effects to disappear.
Individuals can also help prevent acid rain by conserving energy. The less electricity people use in their homes, the fewer chemicals power plants will emit. Vehicles are also major fossil fuel users, so drivers can reduce emissions by using public transportation, carpooling, biking, or simply walking wherever possible.

S: National Geographic – http://goo.gl/JbSNrG (last access: 3 December 2015)

N: 1. – acid (adj): 1620s, “of the taste of vinegar,” from French acide (16c.) or directly from Latin acidus “sour, sharp,” adjective of state from acere “to be sour,” from PIE root *ak– “sharp, pointed”.
– rain (n): From Old English regn “rain,” from Proto-Germanic *regna– (cognates: Old Saxon regan, Old Frisian rein, Middle Dutch reghen, Dutch regen, German regen, Old Norse regn, Gothic rign “rain”), with no certain cognates outside Germanic, unless it is from a presumed PIE *reg– “moist, wet,” which may be the source of Latin rigare “to wet, moisten”.
2. Acid rain is a serious environmental problem that affects large parts of the United States and Canada. Acid rain is particularly damaging to lakes, streams, and forests and the plants and animals that live in these ecosystems.
3. Two elements, sulfur and nitrogen, are primarily responsible for the harmful effects of acid rain.
Sulfur is found as a trace element in coal and oil. When these are burned in power plants and industrial boilers, the sulfur combines with oxygen to form sulfur dioxide (SO₂). Because SO₂ does not react with most chemicals found in the atmosphere, it can travel long distances. Eventually, if it comes in contact with ozone or hydrogen peroxide, it can be converted to sulfur trioxide. Sulfur trioxide can dissolve in water, forming a dilute solution of sulfuric acid.
Nitrogen makes up about 78% of the atmosphere. When heated to the temperatures found in steam boilers and internal combustion engines, it can combine with oxygen from the atmosphere to form nitrogen oxide and nitrogen dioxide (NOx). NOx is the sum of nitrogen oxide and nitrogen dioxide in a given parcel of air. These can dissolve in water, forming weak solutions of nitric and nitrous acids.
4. acid rain: often used as a technically incorrect synonym for acidic deposition or acidic precipitation.

S: 1. OED – http://goo.gl/ypvF4w and http://goo.gl/ATmCjU (last access: 1 December 2015). 2 & 3. EPA – http://goo.gl/1BhEqJ and http://goo.gl/97ScTC (last access: 1 December 2015). 4. TERMIUM PLUS (last access: 4 December 2015).

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CR: air pollution, combustion, contaminant, nitric acid, nitrogen dioxide, nitrogen oxide, rainout, soil pollution, sulfur dioxide.